Advertisements
Advertisements
प्रश्न
The mean of 35 observations is 20, out of which mean of first 18 observations is 15 and mean of last 18 observation is 25. Find the 18th observation.
Advertisements
उत्तर
Mean = `("sum of observations")/("Total number of observations")`
∴ sum of observations = Mean × Total number of observations
∴ sum of 35 observations = 20 × 35
= 700
Sum of first 18th observations = 15 × 18
= 270
Sum of last 18th observations = 25 × 18
= 450
18th observation = Sum of first 18 observations + Sum of last 18 observations - 35th observations
= 270 + 450 − 700
= 720 − 700
= 20
∴ The 18th observation is 20.
APPEARS IN
संबंधित प्रश्न
Following table shows the points of each player scored in four games:
| Player | Game 1 | Game 2 | Game 3 | Game 4 |
| A | 14 | 16 | 10 | 10 |
| B | 0 | 8 | 6 | 4 |
| C | 8 | 11 | Did not play | 13 |
Now answer the following questions:
- Find the mean to determine A’s average number of points scored per game.
- To find the mean number of points per game for C, would you divide the total points by 3 or by 4? Why?
- B played in all the four games. How would you find the mean?
- Who is the best performer?
The mean is one of the numbers in a data.
The data 6, 4, 3, 8, 9, 12, 13, 9 has mean 9.
If `barx` is the mean of x1, x2 ............xn and `bary` is the mean of y1, y2, …….yn and `barz` is the mean of x1, x2 ............xn, y1, y2, ……….yn then `barz` =?
The mean of five numbers is 50, out of which mean of 4 numbers is 46, find the 5th number:
Mean of 100 observations is 40. The 9th observation is 30. If this is replaced by 70 keeping all other observations same, find the new mean.
The following table shows the number of saplings planted by 30 students. Fill in the boxes and find the average number of saplings planted by each student.
| No. of saplings (Scores) xi |
No. of students (frequency) fi |
fi x xi |
| 1 | 4 | 4 |
| 2 | 6 | `square` |
| 3 | 12 | `square` |
| 4 | 8 | `square` |
| N = `square` | ∑fixi = `square` |
Mean `bar "x"` = `square/"N"`
= `square/square`
= `square`
∴ The average number of trees planted `square`
The number of Science and Mathematics projects submitted by Model high school, Nandpur in last 20 years at the state level science exibition is:
2, 3, 4, 1, 2, 3, 1, 5, 4, 2, 3, 1, 3, 5, 4, 3, 2, 2, 3, 2. Prepare a frequency table and find the mean of the data.
The following table shows the electricity (in units) used by 25 families of Eklara village in a month of May. Complete the table and answer the following questions.
| Electricity used (units) `bb(x_i)` |
No. of Families (frequency) `bb(f_i)` |
`bb(f_ix_i)` |
| 30 | 7 | _________ |
| 45 | 2 | __________ |
| 60 | 8 | __________ |
| 75 | 5 | __________ |
| 90 | 3 | __________ |
| N = _________ | `sum f_ix_i` = ______ |
- How many families use 45 units electricity?
- State the score, the frequency of which is 5.
- Find N, and `sum f_ix_i`
- Find the mean of electricity used by each family in the month of May.
In a week, temperature of a certain place is measured during winter are as follows 26°C, 24°C, 28°C, 31°C, 30°C, 26°C, 24°C. Find the mean temperature of the week
The algebraic sum of the deviations of a set of n values from their mean is
The mean of first ten natural numbers is ____________
The marks of 14 students in a science test out of 50 are given below. 34, 23, 10, 45, 44, 47, 35, 37, 41, 30, 28, 32, 45, 39 Find the mean mark
The marks of 14 students in a science test out of 50 are given below. 34, 23, 10, 45, 44, 47, 35, 37, 41, 30, 28, 32, 45, 39 Find the maximum mark obtained
The mean height of 11 students in a group is 150 cm. The heights of the students are 154 cm, 145 cm, Y cm, Y + 4 cm, 160 cm, 151 cm, 149 cm, 149 cm, 150 cm, 144 cm and 140 cm. Find the value of Y and the heights of two students?
The mean of three numbers is 40. All the three numbers are different natural numbers. If lowest is 19, what could be highest possible number of remaining two numbers?
If the arithmetic mean of 8, 4, x, 6, 2, 7 is 5, then the value of x is ______.
Mean of the data is always from the given data.
Mean of the observations can be lesser than each of the observations.
Calculate the Mean, Median and Mode of the following data:
5, 10, 10, 12, 13.
Are these three equal?
