Advertisements
Advertisements
प्रश्न
The mean of five numbers is 30. If one number is excluded, their mean becomes 28. The excluded number is ______.
विकल्प
28
30
35
38
उत्तर
The mean of five numbers is 30. If one number is excluded, their mean becomes 28. The excluded number is 38.
Explanation:
Let x1, x2, x3, x4 and x5 be five numbers and one of the excluded number be x5.
Given, mean of the five numbers = 30
⇒ `(x_1 + x_2 + x_3 + x_4 + x_5)/5 = 30`
⇒ x1 + x2 + x3 + x4 + x5 = 150
⇒ x1 + x2 + x3 + x4 = 150 – x5
On dividing both sides by 4, we get
`(x_1 + x_2 + x_3 + x_4)/4 = (150 - x_5)/4` ...(i)
Given, mean of the four numbers = 28
∴ `(150 - x_5)/4 = 28` ...[From equation (i)]
⇒ 150 – x5 = 112
⇒ x5 = 150 – 112
⇒ x5 = 38
Hence, the excluded number is 38.
APPEARS IN
संबंधित प्रश्न
In a mathematics test given to 15 students, the following marks (out of 100) are recorded:-
41, 39, 48, 52, 46, 62, 54, 40, 96, 52, 98, 40, 42, 52, 60
Find the mean, median and mode of this data.
Find the mean of first 10 even natural numbers.
Find the mean of x, x + 2, x + 4, x +6, x + 8.
Find the median of the following observations : 46, 64, 87, 41, 58, 77, 35, 90, 55, 92, 33. If 92 is replaced by 99 and 41 by 43 in the above data, find the new median?
If the mean of 2, 4, 6, 8, x, y is 5, then find the value of x + y.
If the mean of five observations x, x+2, x+4, x+6, x+8, is 11, then the mean of first three observations is
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 ______.
The class marks of a frequency distribution are given as follows: 15, 20, 25, ... The class corresponding to the class mark 20 is ______.
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:
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 |
