Probability 5 Question 8

8. A box contains 15 green and 10 yellow balls. If 10 balls are randomly drawn one-by-one with replacement, then the variance of the number of green balls drawn is

(a) $\frac{12}{5}$

(b) 6

(c) 4

(d) $\frac{6}{25}$

(2017 Main)

Show Answer

Answer:

Correct Answer: 8. (a)

Solution:

  1. Given box contains 15 green and 10 yellow balls.

$\therefore$ Total number of balls $=15+10=25$

$P($ green balls $)=\frac{15}{25}=\frac{3}{5}=p=$ Probability of success

$P$ (yellow balls) $=\frac{10}{25}=\frac{2}{5}=q=$ Probability of unsuccess and $n=10=$ Number of trials.

$\therefore$ Variance $=n p q=10 \times \frac{3}{5} \times \frac{2}{5}=\frac{12}{5}$



NCERT Chapter Video Solution

Dual Pane