Advertisements
Advertisements
प्रश्न
There are 50 students in a class in which 40 are boys and rest are girls. The average weight of the class is 44 kgs and the average weight of the girls is 40 kgs. Find the average weight of the boys.
उत्तर
We have
n = No., od students in a class = 50
n1 = No., of boys in a class = 40
n2 = No., of girls in a class = 10
`bar"X"_1` = Average weight of boys = ?
`bar"X"_2` = Average weight of girls = 40 kgs.
∴ `bar"X" = ("n"_1 bar"X"_1 + "n"_2 bar"X"_2)/("n"_1 + "n"_2)`
⇒ 44 = `(40bar"X"_1 + 10 xx 40)/(40 + 10)`
⇒ 50 x 44 = `40bar"X"_1 + 400`
⇒ 2200 = `40bar"X" + 400`
⇒ `40bar"X"_1` = 1800
⇒ `bar"X"_1` = 45
Hence, the average weight of boys is 45 kgs.
APPEARS IN
संबंधित प्रश्न
Consider the following distribution of daily wages of 50 worker of a factory.
|
Daily wages (in Rs) |
100 − 120 |
120 − 140 |
140 −1 60 |
160 − 180 |
180 − 200 |
|
Number of workers |
12 |
14 |
8 |
6 |
10 |
Find the mean daily wages of the workers of the factory by using an appropriate method.
Find the mean of the following data:-
| x | 19 | 21 | 23 | 25 | 27 | 29 | 31 |
| f | 13 | 15 | 16 | 18 | 16 | 15 | 13 |
The following table gives the number of children of 150 families in a village. Find the average number of children per family.
| No. of children (x) | 0 | 1 | 2 | 3 | 4 | 5 |
| No. of families (f) | 10 | 21 | 55 | 42 | 15 | 7 |
The marks obtained out of 50, by 102 students in a Physics test are given in the frequency table below:
| Marks(x) | 15 | 20 | 22 | 24 | 25 | 30 | 33 | 38 | 45 |
| Frequency (f) | 5 | 8 | 11 | 20 | 23 | 18 | 13 | 3 | 1 |
Find the average number of marks.
Find the mean of the following data using step-deviation method:
| Class | 500 – 520 | 520 – 540 | 540 – 560 | 560 – 580 | 580 – 600 | 600 – 620 |
| Frequency | 14 | 9 | 5 | 4 | 3 | 5 |
The loans sanctioned by a bank for construction of farm ponds are shown in the following table. Find the mean of the loans.
|
Loan
(Thousand Rupees)
|
40 - 50 | 50 - 60 | 60 - 70 | 70 - 80 | 80 - 90 |
| No. of farm ponds | 13 | 20 | 24 | 36 | 7 |
The mean of 1, 3, 4, 5, 7, 4 is m. The numbers 3, 2, 2, 4, 3, 3, p have mean m − 1 and median q. Then, p + q =
If the arithmetic mean, 7, 8, x, 11, 14 is x, then x =
If the mean of observation \[x_1 , x_2 , . . . . , x_n is x\] then the mean of x1 + a, x2 + a, ....., xn + a is
Find the mean of the following distribution:
| x | 10 | 30 | 50 | 70 | 89 |
| f | 7 | 8 | 10 | 15 | 10 |
