A bag contains 15 balls of which x are blue and the remaining are red. if the number of red balls are increased by 5, the probability of drawing the red balls doubles. find : i) p (red ball) ii) p (blue ball it of 5 extra red balls are actually added)
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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
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
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