Question

There are 2 red and 5 green balls in a bag. If you randomly choose balls one at a time , with replacement , What is the probability of choosing 2 green balls and then 1 red ball?
A. 2/21
B.20/147
C.50/343
D. 5/21

Answer 1

Option C

ANSWER:  

The probability of choosing 2 green balls and 1 red ball is $\frac{50}{343}$

SOLUTION:

Given, there are 2 red and 5 green balls in a bag.

So, there are 7 balls in the bag.

We need to find the probability of choosing 2 green balls and 1 red ball.

Probability of 2 green balls and 1 red ball = probability of 1st green ball $\times$ probability of 2nd green ball x probability of 1 red ball.

Now, probability of 1st green ball = $\frac{\text {number of green balls}}{\text {total number of balls}}$

= $\frac{5}{7}$

because we are replacing after every pick.

Now, probability of red ball = $\frac{\text {number of red balls}}{\text {total number of balls}}$

$=\frac{2}{7}$

Probability of 2 green balls and 1 red ball = $\frac{5}{7} \times \frac{5}{7} \times \frac{2}{7}$

$=\frac{5 \times 5 \times 2}{7 \times 7 \times 7}$

$=\frac{50}{343}$

Hence, the probability of choosing 2 green balls and 1 red ball is $\frac{50}{343}$

Answer 2

Answer:

D is the answer

Step-by-step explanation: