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

Option C

ANSWER:  

The probability of choosing 2 green balls and 1 red ball is

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 probability of 2nd green ball x probability of 1 red ball.

Now, probability of 1st green ball =

=

because we are replacing after every pick.

Now, probability of red ball =

Probability of 2 green balls and 1 red ball =

Hence, the probability of choosing 2 green balls and 1 red ball is

1/4 and 8/3 because:

the reciprocal if 4 is 1/4 because 4 is used as 4/1 and the opposite of that is 1/4. the opposite of 3/8 is 8/3 so that is the answer.

answer

the correct answer is

explanation

the given function is

the excluded values are obtained by solving:

we factor to obtain:

the excluded values are