Question

A bag contains 5 red balls and n green balls. If the probability of drawing a green ball is three times that of a red ball, then the value of n is ______.

Options

• 18

• 15

• 10

• 20

Answer 1

A bag contains 5 red balls and n green balls. If the probability of drawing a green ball is three times that of a red ball, then the value of n is 15.

Explanation:

Given, Number of red ball = 5

Number of green ball = n

∴ Total ball = n + 5

Now P(red ball) = `5/(n + 5)`

and P(green ball) = `n/(n + 5)`

Now, according to the question

`n/(n + 5) = (3 xx 5)/(n + 5)`

n = 15

So, number of green ball = 15