Question

A bad contains 15 balls of which X is red. Write an expression for the probability that a ball drawn from the bad is red. When 5 more red balls are added to the bag, the probability becomes 3/4. Find the value of X.

Answer 1

10

Explanation:

The current probability of picking a red ball is
`(x)/(15)`. When 5 more balls are added, the probability is 3/4. We can write a ratio for this problem:

`(x+5)/(15+5) = (3)/(4)`

When using cross multiplication to solve this, you get 3 * 20 = 4(x+5).

60 = 4x + 20

40 = 4x

x = 10 red balls