Question

A bag contains 15 balls out of which x are blue and the remaining are red.If the no of balls increased by 5, the probability of drawing the red balls doubles.Find the probability of:
1) P (red ball)
2) P (blue ball)
3) P (blue ball if 5 extra red balls are actually added)

Answer 1

P(red. Ball) = 15-x/ 15
P(blue ball)= x/15

Q
When five ball are added
P(re d)= 20-x/20
P( blue)= x+5/20


According to question
2(15-x/15)= 20-x/20
300=25x
12=x
Substitute this in p of blue when 5 balls are added
P(blue)= 12+5/20=17/20