# NCERT solutions for Mathematics Exemplar Class 9 chapter 14 - Statistics & Probability [Latest edition]

#### Chapters ## Chapter 14: Statistics & Probability

Exercise 14.1Exercise 14.2Exercise 14.3Exercise 14.4
Exercise 14.1 [Pages 131 - 136]

### NCERT solutions for Mathematics Exemplar Class 9 Chapter 14 Statistics & Probability Exercise 14.1 [Pages 131 - 136]

#### Choose the correct alternative:

Exercise 14.1 | Q 1 | Page 131

The class mark of class 90 – 120 is ______.

• 90

• 105

• 115

• 120

Exercise 14.1 | Q 2 | Page 131

The range of the data: 25, 18, 20, 22, 16, 6, 17, 15, 12, 30, 32, 10, 19, 8, 11, 20 is  ______.

• 10

• 15

• 18

• 26

Exercise 14.1 | Q 3 | Page 131

In a frequency distribution, the mid-value of a class is 10 and the width of the class is 6. The lower limit of the class is ______.

• 6

• 7

• 8

• 12

Exercise 14.1 | Q 4 | Page 132

The width of each of five continuous classes in a frequency distribution is 5 and the lower class-limit of the lowest class is 10. The upper class-limit of the highest class is ______.

• 15

• 25

• 35

• 40

Exercise 14.1 | Q 5 | Page 132

Let m be the mid-point and l be the upper-class limit of a class in a continuous frequency distribution. The lower class limit of the class is ______.

• 2m + l

• 2m – l

• m – l

• m – 2l

Exercise 14.1 | Q 6 | Page 132

The class marks of a frequency distribution are given as follows: 15, 20, 25, ... The class corresponding to the class mark 20 is ______.

• 12.5 – 17.5

• 17.5 – 22.5

• 18.5 – 21.5

• 19.5 – 20.5

Exercise 14.1 | Q 7 | Page 132

In the class intervals 10 – 20, 20 – 30, the number 20 is included in ______.

• 10 – 20

• 20 – 30

• Both the intervals

• None of these

Exercise 14.1 | Q 8 | Page 132

A grouped frequency table with class intervals of equal sizes using 250 – 270 (270 not included in this interval) as one of the class interval is constructed for the following data: 268, 220, 368, 258, 242, 310, 272, 342, 310, 290, 300, 320, 319, 304, 402, 318, 406, 292, 354, 278, 210, 240, 330, 316, 406, 215, 258, 236. The frequency of the class 310 – 330 is ______.

• 4

• 5

• 6

• 7

Exercise 14.1 | Q 9 | Page 132

A grouped frequency distribution table with classes of equal sizes using 63 – 72 (72 included) as one of the class is constructed for the following data: 30, 32, 45, 54, 74, 78, 108, 112, 66, 76, 88, 40, 14, 20, 15, 35, 44, 66, 75, 84, 95, 96, 102, 110, 88, 74, 112, 14, 34, 44. The number of classes in the distribution will be ______.

• 9

• 10

• 11

• 12

Exercise 14.1 | Q 10 | Page 132

To draw a histogram to represent the following frequency distribution:

 Class interval 5 – 10 10 – 15 15 – 25 25 – 45 45 – 75 Frequency 6 12 10 8 15

the adjusted frequency for the class 25 – 45 is ______.

• 6

• 5

• 3

• 2

Exercise 14.1 | Q 11 | Page 133

The mean of five numbers is 30. If one number is excluded, their mean becomes 28. The excluded number is ______.

• 28

• 30

• 35

• 38

Exercise 14.1 | Q 12 | Page 133

If the mean of the observations: x, x + 3, x + 5, x + 7, x + 10 is 9, the mean of the last three observations is ______.

• 10 1/3

• 10 2/3

• 11 1/3

• 11 2/3

Exercise 14.1 | Q 13 | Page 133

If barx represents the mean of n observations x1, x2, ..., xn, then value of sum_(i = 1)^n (x_i - barx) is ______.

• –1

• 0

• 1

• n – 1

Exercise 14.1 | Q 14 | Page 133

If each observation of the data is increased by 5, then their mean ______.

• Remains the same

• Becomes 5 times the original mean

• Is decreased by 5

• Is increased by 5

Exercise 14.1 | Q 15 | Page 133

Let barx be the mean of x1, x2, ..., xn and y the mean of y1, y2, ..., yn. If z is the mean of x1, x2, ..., xn, y1, y2, ..., yn, then z is equal to ______.

• barx + bary

• (barx + bary)/2

• (barx + bary)/n

• (barx + bary)/(2n)

Exercise 14.1 | Q 16 | Page 133

If barx is the mean of x1, x2, ..., xn, then for a ≠ 0, the mean of ax1, ax2, ..., axn, x_1/a, x_2/a, ..., x_n/a is ______.

• (a + 1/a)barx

• (a + 1/a) barx/2

• (a + 1/a)barx/n

• ((a + 1/a)barx)/(2n)

Exercise 14.1 | Q 17 | Page 133

If barx_1, barx_2, barx_3,  ..., barx_n are the means of n groups with n1, n2, ..., nn number of observations respectively, then the mean x of all the groups taken together is given by ______.

• sum_(i = 1)^n n_i barx_i

• (sum_(i = 1)^n n_i barx_i)/n^2

• (sum_(i = 1)^n n_i barx_i)/(sum_(i = 1)^n n_i)

• (sum_(i = 1)^n n_i barx_i)/(2n)

Exercise 14.1 | Q 18 | Page 134

The mean of 100 observations is 50. If one of the observations which was 50 is replaced by 150, the resulting mean will be ______.

• 50.5

• 51

• 51.5

• 52

Exercise 14.1 | Q 19 | Page 134

There are 50 numbers. Each number is subtracted from 53 and the mean of the numbers so obtained is found to be –3.5. The mean of the given numbers is ______.

• 46.5

• 49.5

• 53.5

• 56.5

Exercise 14.1 | Q 20 | Page 134

The mean of 25 observations is 36. Out of these observations if the mean of first 13 observations is 32 and that of the last 13 observations is 40, the 13th observation is ______.

• 23

• 36

• 38

• 40

Exercise 14.1 | Q 21 | Page 134

The median of the data 78, 56, 22, 34, 45, 54, 39, 68, 54, 84 is ______.

• 45

• 49.5

• 54

• 56

Exercise 14.1 | Q 22 | Page 134

For drawing a frequency polygon of a continous frequency distribution, we plot the points whose ordinates are the frequencies of the respective classes and abcissae are respectively ______.

• Upper limits of the classes

• Lower limits of the classes

• Class marks of the classes

• Upper limits of proceeding classes

Exercise 14.1 | Q 23 | Page 134

Median of the following numbers 4, 4, 5, 7, 6, 7, 7, 12, 3 is ______.

• 4

• 5

• 6

• 7

Exercise 14.1 | Q 24 | Page 134

Mode of the data 15, 14, 19, 20, 14, 15, 16, 14, 15, 18, 14, 19, 15, 17, 15 is ______.

• 14

• 15

• 16

• 17

Exercise 14.1 | Q 25 | Page 134

In a sample study of 642 people, it was found that 514 people have a high school certificate. If a person is selected at random, the probability that the person has a high school certificate is ______.

• 0.5

• 0.6

• 0.7

• 0.8

Exercise 14.1 | Q 26 | Page 135

In a survey of 364 children aged 19 – 36 months, it was found that 91 liked to eat potato chips. If a child is selected at random, the probability that he/she does not like to eat potato chips, is ______.

• 0.25

• 0.50

• 0.75

• 0.80

Exercise 14.1 | Q 27 | Page 135

In a medical examination of students of a class, the following blood groups are recorded:

 Blood group A AB B 0 Number of students 10 13 12 5

A student is selected at random from the class. The probability that he/she has blood group B, is ______.

• 1/4

• 13/40

• 3/10

• 1/8

Exercise 14.1 | Q 28 | Page 135

Two coins are tossed 1000 times and the outcomes are recorded as below:

 Number of heads 2 1 0 Frequency 200 550 250

Based on this information, the probability for at most one head is ______.

• 1/5

• 1/4

• 4/5

• 3/4

Exercise 14.1 | Q 29 | Page 135

80 bulbs are selected at random from a lot and their life time (in hrs) is recorded in the form of a frequency table given below:

 Life time (in hours) 300 500 700 900 1100 Frequency 10 12 23 25 10

One bulb is selected at random from the lot. The probability that its life is 1150 hours, is ______.

• 1/80

• 7/16

• 0

• 1

Exercise 14.1 | Q 30 | Page 136

Refer to Q.29 above: The probability that bulbs selected randomly from the lot has life less than 900 hours is ______.

• 11/40

• 5/16

• 7/16

• 9/16

Exercise 14.2 [Pages 136 - 138]

### NCERT solutions for Mathematics Exemplar Class 9 Chapter 14 Statistics & Probability Exercise 14.2 [Pages 136 - 138]

Exercise 14.2 | Q 1 | Page 136

The frequency distribution:

 Marks 0 – 20 20 – 40 40 – 60 60 – 100 Number of Students 10 15 20 25

has been represented graphically as follows: Do you think this representation is correct? Why?

Exercise 14.2 | Q 2 | Page 137

In a diagnostic test in mathematics given to students, the following marks (out of 100) are recorded: 46, 52, 48, 11, 41, 62, 54, 53, 96, 40, 98, 44 Which ‘average’ will be a good representative of the above data and why?

Exercise 14.2 | Q 3 | Page 137

A child says that the median of 3, 14, 18, 20, 5 is 18. What doesn’t the child understand about finding the median?

Exercise 14.2 | Q 4 | Page 137

A football player scored the following number of goals in the 10 matches: 1, 3, 2, 5, 8, 6, 1, 4, 7, 9
Since the number of matches is 10 (an even number), therefore, the median

= (5^(th)  observation + 6^(th)  observation)/2

= (8 + 6)/2 = 7
Is it the correct answer and why?

Exercise 14.2 | Q 5 | Page 137

Is it correct to say that in a histogram, the area of each rectangle is proportional to the class size of the corresponding class interval? If not, correct the statement.

Exercise 14.2 | Q 6 | Page 137

The class marks of a continuous distribution are: 1.04, 1.14, 1.24, 1.34, 1.44, 1.54 and 1.64 Is it correct to say that the last interval will be 1.55 – 1.73? Justify your answer.

Exercise 14.2 | Q 7 | Page 138

30 children were asked about the number of hours they watched TV programmes last week. The results are recorded as under:

 Number of hours 0 – 5 5 – 10 10 – 15 15 – 20 Frequency 8 16 4 2

Can we say that the number of children who watched TV for 10 or more hours a week is 22? Justify your answer.

Exercise 14.2 | Q 8 | Page 138

Can the experimental probability of an event be a negative number? If not, why?

Exercise 14.2 | Q 9 | Page 138

Can the experimental probability of an event be greater than 1? Justify your answer.

Exercise 14.2 | Q 10 | Page 138

As the number of tosses of a coin increases, the ratio of the number of heads to the total number of tosses will be 1/2. Is it correct? If not, write the correct one.

Exercise 14.3 [Pages 140 - 144]

### NCERT solutions for Mathematics Exemplar Class 9 Chapter 14 Statistics & Probability Exercise 14.3 [Pages 140 - 144]

Exercise 14.3 | Q 1 | Page 140

The blood groups of 30 students are recorded as follows: A, B, O, A, AB, O, A, O, B, A, O, B, A, AB, B, A, AB, B, A, A, O, A, AB, B, A, O, B, A, B, A Prepare a frequency distribution table for the data.

Exercise 14.3 | Q 2 | Page 140

The value of π upto 35 decimal places is given below: 3. 14159265358979323846264338327950288 Make a frequency distribution of the digits 0 to 9 after the decimal point.

Exercise 14.3 | Q 3 | Page 140

The scores (out of 100) obtained by 33 students in a mathematics test are as follows:
69, 48, 84, 58, 48, 73, 83, 48, 66, 58, 84
66, 64, 71, 64, 66, 69, 66, 83, 66, 69, 71
81, 71, 73, 69, 66, 66, 64, 58, 64, 69, 69
Represent this data in the form of a frequency distribution.

Exercise 14.3 | Q 4 | Page 140

Prepare a continuous grouped frequency distribution from the following data:

 Mid-point Frequency 5 4 15 8 25 13 35 12 45 6

Also find the size of class intervals.

Exercise 14.3 | Q 5 | Page 141

Convert the given frequency distribution into a continuous grouped frequency distribution:

 Class interval Frequency 150 – 153 7 154 – 157 7 158 – 161 15 162 – 165 10 166 – 169 5 170 – 173 6

In which intervals would 153.5 and 157.5 be included?

Exercise 14.3 | Q 6 | Page 141

The expenditure of a family on different heads in a month is given below:

 Head Food Education Clothing House Rent Others Savings Expenditure(in Rs) 4000 2500 1000 3500 2500 1500

Draw a bar graph to represent the data above.

Exercise 14.3 | Q 7 | Page 141

Expenditure on Education of a country during a five year period (2002-2006), in crores of rupees, is given below:

 Elementary education 240 Secondary Education 120 University Education 190 Teacher’s Training 20 Social Education 10 Other Educational Programmes 115 Cultural programmes 25 Technical Education 125

Represent the information above by a bar graph.

Exercise 14.3 | Q 8 | Page 141

The following table gives the frequencies of most commonly used letters a, e, i, o, r, t, u from a page of a book:

 Letters a e i o r t u Frequency 75 125 80 70 80 95 75

Represent the information above by a bar graph.

Exercise 14.3 | Q 9 | Page 142

If the mean of the following data is 20.2, find the value of p:

 x 10 15 20 25 30 f 6 8 p 10 6
Exercise 14.3 | Q 10 | Page 142

Obtain the mean of the following distribution:

 Frequency Variable 4 4 8 6 14 8 11 10 3 12
Exercise 14.3 | Q 11 | Page 142

A class consists of 50 students out of which 30 are girls. The mean of marks scored by girls in a test is 73 (out of 100) and that of boys is 71. Determine the mean score of the whole class.

Exercise 14.3 | Q 12 | Page 142

Mean of 50 observations was found to be 80.4. But later on, it was discovered that 96 was misread as 69 at one place. Find the correct mean.

Exercise 14.3 | Q 13 | Page 142

Ten observations 6, 14, 15, 17, x + 1, 2x – 13, 30, 32, 34, 43 are written in an ascending order. The median of the data is 24. Find the value of x.

Exercise 14.3 | Q 14 | Page 142

The points scored by a basket ball team in a series of matches are as follows: 17, 2, 7, 27, 25, 5, 14, 18, 10, 24, 48, 10, 8, 7, 10, 28 Find the median and mode for the data

Exercise 14.3 | Q 15 | Page 142

In figure, there is a histogram depicting daily wages of workers in a factory. Construct the frequency distribution table. Exercise 14.3 | Q 16.(i) | Page 143

A company selected 4000 households at random and surveyed them to find out a relationship between income level and the number of television sets in a home. The information so obtained is listed in the following table:

 Monthly income (in Rs) Number of Television/household 0 1 2 Above 2 < 10000 20 80 10 0 10000 – 14999 10 240 60 0 15000 – 19999 0 380 120 30 20000 – 24999 0 520 370 80 25000 and above 0 1100 760 220

Find the probability of a household earning Rs 10000 – Rs 14999 per year and having exactly one television.

Exercise 14.3 | Q 16.(ii) | Page 143

A company selected 4000 households at random and surveyed them to find out a relationship between income level and the number of television sets in a home. The information so obtained is listed in the following table:

 Monthly income (in Rs) Number of Television/household 0 1 2 Above 2 < 10000 20 80 10 0 10000 – 14999 10 240 60 0 15000 – 19999 0 380 120 30 20000 – 24999 0 520 370 80 25000 and above 0 1100 760 220

Find the probability of a household earning Rs 25000 and more per year and owning 2 televisions.

Exercise 14.3 | Q 16.(iii) | Page 143

A company selected 4000 households at random and surveyed them to find out a relationship between income level and the number of television sets in a home. The information so obtained is listed in the following table:

 Monthly income (in Rs) Number of Television/household 0 1 2 Above 2 < 10000 20 80 10 0 10000 – 14999 10 240 60 0 15000 – 19999 0 380 120 30 20000 – 24999 0 520 370 80 25000 and above 0 1100 760 220

Find the probability of a household not having any television.

Exercise 14.3 | Q 17.(i) | Page 143

Two dice are thrown simultaneously 500 times. Each time the sum of two numbers appearing on their tops is noted and recorded as given in the following table:

 Sum Frequency 2 14 3 30 4 42 5 55 6 72 7 75 8 70 9 53 10 46 11 28 12 15

If the dice are thrown once more, what is the probability of getting a sum 3?

Exercise 14.3 | Q 17.(ii) | Page 143

Two dice are thrown simultaneously 500 times. Each time the sum of two numbers appearing on their tops is noted and recorded as given in the following table:

 Sum Frequency 2 14 3 30 4 42 5 55 6 72 7 75 8 70 9 53 10 46 11 28 12 15

If the dice are thrown once more, what is the probability of getting a sum more than 10?

Exercise 14.3 | Q 17.(iii) | Page 143

Two dice are thrown simultaneously 500 times. Each time the sum of two numbers appearing on their tops is noted and recorded as given in the following table:

 Sum Frequency 2 14 3 30 4 42 5 55 6 72 7 75 8 70 9 53 10 46 11 28 12 15

If the dice are thrown once more, what is the probability of getting a sum less than or equal to 5?

Exercise 14.3 | Q 17.(iv) | Page 143

Two dice are thrown simultaneously 500 times. Each time the sum of two numbers appearing on their tops is noted and recorded as given in the following table:

 Sum Frequency 2 14 3 30 4 42 5 55 6 72 7 75 8 70 9 53 10 46 11 28 12 15

If the dice are thrown once more, what is the probability of getting a sum between 8 and 12?

Exercise 14.3 | Q 18.(i) | Page 144

Bulbs are packed in cartons each containing 40 bulbs. Seven hundred cartons were examined for defective bulbs and the results are given in the following table:

 Number of defective bulbs 0 1 2 3 4 5 6 more than 6 Frequency 400 180 48 41 18 8 3 2

One carton was selected at random. What is the probability that it has no defective bulb?

Exercise 14.3 | Q 18.(ii) | Page 144

Bulbs are packed in cartons each containing 40 bulbs. Seven hundred cartons were examined for defective bulbs and the results are given in the following table:

 Number of defective bulbs 0 1 2 3 4 5 6 more than 6 Frequency 400 180 48 41 18 8 3 2

One carton was selected at random. What is the probability that it has defective bulbs from 2 to 6?

Exercise 14.3 | Q 8.(iii) | Page 144

Bulbs are packed in cartons each containing 40 bulbs. Seven hundred cartons were examined for defective bulbs and the results are given in the following table:

 Number of defective bulbs 0 1 2 3 4 5 6 more than 6 Frequency 400 180 48 41 18 8 3 2

One carton was selected at random. What is the probability that it has defective bulbs less than 4?

Exercise 14.3 | Q 19.(i) | Page 144

Over the past 200 working days, the number of defective parts produced by a machine is given in the following table:

 Number of defective parts 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Days 50 32 22 18 12 12 10 10 10 8 6 6 2 2

Determine the probability that tomorrow’s output will have no defective part

Exercise 14.3 | Q 19.(ii) | Page 144

Over the past 200 working days, the number of defective parts produced by a machine is given in the following table:

 Number of defective parts 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Days 50 32 22 18 12 12 10 10 10 8 6 6 2 2

Determine the probability that tomorrow’s output will have atleast one defective part

Exercise 14.3 | Q 19.(iii) | Page 144

Over the past 200 working days, the number of defective parts produced by a machine is given in the following table:

 Number of defective parts 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Days 50 32 22 18 12 12 10 10 10 8 6 6 2 2

Determine the probability that tomorrow’s output will have not more than 5 defective parts

Exercise 14.3 | Q 19.(iv) | Page 144

Over the past 200 working days, the number of defective parts produced by a machine is given in the following table:

 Number of defective parts 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Days 50 32 22 18 12 12 10 10 10 8 6 6 2 2

Determine the probability that tomorrow’s output will have more than 13 defective parts

Exercise 14.3 | Q 20.(i) | Page 144

A recent survey found that the ages of workers in a factory is distributed as follows:

 Age (in years) 20 – 29 30 – 39 40 – 49 50 – 59 60 and above Number of workers 38 27 86 46 3

If a person is selected at random, find the probability that the person is 40 years or more

Exercise 14.3 | Q 20.(ii) | Page 144

A recent survey found that the ages of workers in a factory is distributed as follows:

 Age (in years) 20 – 29 30 – 39 40 – 49 50 – 59 60 and above Number of workers 38 27 86 46 3

If a person is selected at random, find the probability that the person is under 40 years

Exercise 14.3 | Q 20.(iii) | Page 144

A recent survey found that the ages of workers in a factory is distributed as follows:

 Age (in years) 20 – 29 30 – 39 40 – 49 50 – 59 60 and above Number of workers 38 27 86 46 3

If a person is selected at random, find the probability that the person is having age from 30 to 39 years

Exercise 14.3 | Q 20.(iv) | Page 144

A recent survey found that the ages of workers in a factory is distributed as follows:

 Age (in years) 20 – 29 30 – 39 40 – 49 50 – 59 60 and above Number of workers 38 27 86 46 3

If a person is selected at random, find the probability that the person is under 60 but over 39 years

Exercise 14.4 [Pages 147 - 149]

### NCERT solutions for Mathematics Exemplar Class 9 Chapter 14 Statistics & Probability Exercise 14.4 [Pages 147 - 149]

Exercise 14.4 | Q 1 | Page 147

The following are the marks (out of 100) of 60 students in mathematics. 16, 13, 5, 80, 86, 7, 51, 48, 24, 56, 70, 19, 61, 17, 16, 36, 34, 42, 34, 35, 72, 55, 75, 31, 52, 28, 72, 97, 74, 45, 62, 68, 86, 35, 85, 36, 81, 75, 55, 26, 95, 31, 7, 78, 92, 62, 52, 56, 15, 63, 25, 36, 54, 44, 47, 27, 72, 17, 4, 30. Construct a grouped frequency distribution table with width 10 of each class starting from 0 – 9.

Exercise 14.4 | Q 2 | Page 147

Refer to Q1 above. Construct a grouped frequency distribution table with width 10 of each class, in such a way that one of the classes is 10 – 20 (20 not included).

Exercise 14.4 | Q 3 | Page 147

Draw a histogram of the following distribution:

 Heights (in cm) Number of students 150 – 153 7 153 – 156 8 156 – 159 14 159 – 162 10 162 – 165 6 165 – 168 5
Exercise 14.4 | Q 4 | Page 147

Draw a histogram to represent the following grouped frequency distribution:

 Ages (in years) Number of teachers 20 – 24 10 25 – 29 28 30 – 34 32 35 – 39 48 40 – 44 50 45 – 49 35 50 – 54 12
Exercise 14.4 | Q 5 | Page 148

The lengths of 62 leaves of a plant are measured in millimetres and the data is represented in the following table:

 Length (in mm) Number of leaves 118 – 126 8 127 – 135 10 136 – 144 12 145 – 153 17 154 – 162 7 163 – 171 5 172 – 180 3

Draw a histogram to represent the data above.

Exercise 14.4 | Q 6 | Page 148

The marks obtained (out of 100) by a class of 80 students are given below:

 Marks Number of students 10 – 20 6 20 – 30 17 30 – 50 15 50 – 70 16 70 – 100 26

Construct a histogram to represent the data above.

Exercise 14.4 | Q 7 | Page 148

Following table shows a frequency distribution for the speed of cars passing through at a particular spot on a highway:

 Class interval (km/h) Frequency 30 – 40 3 40 – 50 6 50 – 60 25 60 – 70 65 70 – 80 50 80 – 90 28 90 – 100 14

Draw a histogram and frequency polygon representing the data above.

Exercise 14.4 | Q 8 | Page 149

Refer to Q.7: Draw the frequency polygon representing the above data without drawing the histogram.

Exercise 14.4 | Q 9 | Page 149

Following table gives the distribution of students of sections A and B of a class according to the marks obtained by them.

 Section A Section B Marks Frequency Marks Frequency 0 – 15 5 0 – 15 3 15 – 30 12 15 – 30 16 30 – 45 28 30 – 45 25 45 – 60 30 45 – 60 27 60 –75 35 60 – 75 40 75 – 90 13 75 – 90 10

Represent the marks of the students of both the sections on the same graph by two frequency polygons. What do you observe?

Exercise 14.4 | Q 10 | Page 149

The mean of the following distribution is 50.

 x f 10 17 30 5a + 3 50 32 70 7a – 11 90 19

Find the value of a and hence the frequencies of 30 and 70.

Exercise 14.4 | Q 11 | Page 149

The mean marks (out of 100) of boys and girls in an examination are 70 and 73, respectively. If the mean marks of all the students in that examination is 71, find the ratio of the number of boys to the number of girls.

Exercise 14.4 | Q 12 | Page 149

A total of 25 patients admitted to a hospital are tested for levels of blood sugar, (mg/dl) and the results obtained were as follows:

 87 71 83 67 85 77 69 76 65 85 85 54 70 68 80 73 78 68 85 73 81 78 81 77 75

Find mean, median and mode (mg/dl) of the above data.

## Chapter 14: Statistics & Probability

Exercise 14.1Exercise 14.2Exercise 14.3Exercise 14.4 ## NCERT solutions for Mathematics Exemplar Class 9 chapter 14 - Statistics & Probability

NCERT solutions for Mathematics Exemplar Class 9 chapter 14 (Statistics & Probability) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Mathematics Exemplar Class 9 solutions in a manner that help students grasp basic concepts better and faster.

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