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Question
Use graph paper for this question. The following table shows the weights in gm of a sample of 100 potatoes taken from a large consignment:
| Weight (gms) | Frequency |
| 50 - 60 | 8 |
| 60 - 70 | 10 |
| 70 - 80 | 12 |
| 80 - 90 | 16 |
| 90 - 100 | 18 |
| 100 - 110 | 14 |
| 110 - 120 | 12 |
| 120 - 130 | 10 |
(i) Calculate the cumulative frequencies.
(ii) Draw the cumulative frequency curve and form it determine the median weights of the potatoes.
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Solution
(i) The cumulative frequencies table is :
| Weight (gm) | Number of potatoes (f) | Cummulative Frequency |
| 50 - 60 | 8 | 8 |
| 60 - 70 | 10 | 18 |
| 70 - 80 | 12 | 30 |
| 80 - 90 | 16 | 46 |
| 90 - 100 | 18 | 64 |
| 100 - 110 | 14 | 78 |
| 110 - 120 | 12 | 90 |
| 120 - 130 | 10 | 100 |
(ii) Plotting the points (60, 8), (70, 18), (80, 30), (90, 46), (100, 64), (110, 78), (120, 90), (130, 100) and joining them by a free hand we get cummulative frequency curve as shown the figure. To complete it, we join the curve to the point (lower limit of the lowest class, 50) i.e., (50, 0).
The positive of median is given by `"n"/(2) = (100)/(2)` = 50.
On vertical axis form the mark of 50. Draw the horizontal line cutting the curve at a point for which the abscissa is 92 gms. Which is the value of the median.
RELATED QUESTIONS
The following table gives the height of trees:
| Height | No. of trees |
| Less than 7 Less than 14 Less than 21 Less than 28 Less than 35 Less than 42 Less than 49 Less than 56 |
26 57 92 134 216 287 341 360 |
Draw 'less than' ogive and 'more than' ogive.
The annual profits earned by 30 shops of a shopping complex in a locality give rise to the following distribution:
| Profit (in lakhs in Rs) | Number of shops (frequency) |
| More than or equal to 5 More than or equal to 10 More than or equal to 15 More than or equal to 20 More than or equal to 25 More than or equal to 30 More than or equal to 35 |
30 28 16 14 10 7 3 |
Draw both ogives for the above data and hence obtain the median.
Draw a cumulative frequency curve (ogive) for the following distributions:
| Class Interval | 10 – 15 | 15 – 20 | 20 – 25 | 25 – 30 | 30 – 35 | 35 – 40 |
| Frequency | 10 | 15 | 17 | 12 | 10 | 8 |
Construct a frequency distribution table for the following distributions:
| Marks (less than) | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
| Cumulative frequency | 0 | 7 | 28 | 54 | 71 | 84 | 105 | 147 | 180 | 196 | 200 |
Find the correct answer from the alternatives given.
Cumulative frequencies in a grouped frequency table are useful to find ______.
Draw an ogive for the following :
| Marks obtained | More than 10 | More than 20 | More than 30 | More than 40 | More than 50 |
| No. of students | 8 | 25 | 38 | 50 | 67 |
Find the width of class 35 - 45.
The following is the frequency distribution with unknown frequencies :
| Class | 60-70 | 70-80 | 80-90 | 90-100 | Total |
| frequency | `"a"/2` | `(3"a")/2` | 2a | a | 50 |
Find the value of a, hence find the frequencies. Draw a histogram and frequency polygon on the same coordinate system.
Using a graph paper, drawn an Ogive for the following distribution which shows a record of the weight in kilograms of 200 students.
| Weight | Frequency |
| 40 - 45 | 5 |
| 45 - 50 | 17 |
| 50 - 55 | 22 |
| 55 - 60 | 45 |
| 60 - 65 | 51 |
| 65 - 70 | 31 |
| 70 - 75 | 20 |
| 75 - 80 | 9 |
Use your ogive to estimate the following:
(i) The percentage of students weighing 55kg or more.
(ii) The weight above which the heaviest 30% of the students fall.
(iii) The number of students who are:
(1) under-weight and
(2) over-weight, if 55·70 kg is considered as standard weight.
The frequency distribution of scores obtained by 230 candidates in a medical entrance test is as ahead:
| Cost of living Index | Number of Months |
| 400 - 450 | 20 |
| 450 - 500 | 35 |
| 500 - 550 | 40 |
| 550 - 600 | 32 |
| 600 - 650 | 24 |
| 650 - 700 | 27 |
| 700 - 750 | 18 |
| 750 - 800 | 34 |
| Total | 230 |
Draw a cummulative polygon (ogive) to represent the above data.
