Question

A toy box contains eight green balls and four purple balls. Suppose you choose a ball at random and then replace it by putting it back in the toy box. You then choose a second ball. What is the probability that you have selected a green ball and then a purple ball?
Option A: 2/9
Option B: 1/2
Option C: 1/3
Option D: 2/3

Answer 1

Answer: C.  $\dfrac{1}{3}$

Step-by-step explanation:

Given: Box contains 8 green balls and 4 purple balls.

Total balls = 8+4 = 12

event 1 = first picking green ball

event 2 = second picking purple balls.

As first ball was replaced, that means both events are independent.

Probability that you have selected a green ball and then a purple ball = P(purple ball )

Formula for probability = $\dfrac{\text{favorable outcomes}}{\text{total outcomes}}$

Probability of selecting a purple ball (second pick)= $\dfrac{4}{12}$

$=\dfrac{1}{3}$

The required probability $=\dfrac{1}{3}$, so C is correct option.