Question

In class of 100 sutdents, the average amount of
pocket money is Rs. 35 per student. If the average
is Rs 25 for girls and Rs 50 for boys, then the
number of girls in the class is:
(a)20 (b) 40 (c)60 (d) 80​

Answer 1

Answer:

B

Step-by-step explanation:

the number of girls in class =40

boys=60

Answer 2

Let the number of girls in the class = y

Therefore, Number of boys in the class = 100 - y

Now, $\overline{x_1} = 25,n_1 = y, \overline{x_2} =50,n_2 = 100 - y$

and $\overline{x} = 35, n_1 + n_2 = 100$

$35 = \frac{25\times y + 50\times (100 - y)}{100}$

3500 = 25y + 5000 - 50y

25y    = 1500 => y = 60

=> Number of girls in the class = 60

Amannnscharlie