a bag contains 15 balls of which x are blue and remaining are red if the number of red - Maths - Probability

Question

a bag contains 15 balls of which x are blue and remaining are red
if the number of red balls are increased by 5,the probability of
red ball doubles find x

Shadhir · Accepted Answer

In First Case,

No Of Balls = 15
No Of Blue Balls = x
No Of Red Balls = 15 - x
Probability of taking a red ball is; P(E) = 15 - x
15

After 5 red balls are added,
No of balls = 15 + 5 = 20
No of blue balls = x
No of Red Balls = (15 - x) + 5 = 20 - x
Probability of taking a red ball is; P(E) = 20 - x
20

According to your question, 15 - x x 2 = 20 - x
15 20

30 - 2x = 20 - x
15 20

600 - 40 x = 300 - 15 x
​ 300 =25 x
x = 12

a bag contains 15 balls of which x are blue and remaining are red. if the number of red balls are increased by 5,the probability of red ball doubles.find x