Question

A bag of athletics supplies contains 12 baseballs and 8 footballs. One ball is chosen at random and replace two times. What is the probability of choosing a football both time?
A 1/10
B 14/95
C 4/25
D 2/5

Answer 1

Answer:

Initially, total number of balls =12

No. of black balls =x

So, P(black ball) =

12

x

If 6 more black balls are added, total number of balls =12+6=18

NO. of black balls =x+6

P(black ball) =

18

x+6

Given the probability of drawing a black ball is now double of what it was before

So,

12

2x

=

18

(x+6)

6

x

=

18

(x+6)

3x=x+6

2x=6

x=3

So, the number of black balls present initially =3.