A bag contain 12balls out of which x are black ball.find probablity of getting a black ball if one ball is drawn .if 6 more blacks ball are added in the bags, the probability of getting black ball will be double.find x
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Answers
Step-by-step explanation:
N(s) =12
N(e) =x
P(E) =X/12
6 MORE BALLS ARE ADDED
N(S) =18
Answer:
1/4
Step-by-step explanation:
Probability = Number of possible outcomes / Total number of outcomes
Total Number of balls = 12
Let the number of black balls = x
Probability of getting black ball = Number of possible outcomes / Total number of outcomes
= x/12
If 6 more black balls are put in the box, the probability of drawing a black ball is now double what it was before,
Total number of balls = 12 + 6
Number of black balls = x + 6
Now,
2 × Probability of drawing black ball before = probability of drawing black ball
2 × Probability of drawing black ball before = Number of possible outcomes /Total number of outcomes
2(x/12) = (x + 6)/18
3x = x + 6
3x - x = 6
2x = 6
x = 3
Hence, previously, the number of black balls was 3.
Thus, the probability of getting a black ball initially was x/12 = 3/12 = 1/4. We know that,
Probability = Number of possible outcomes / Total number of outcomes
Total Number of balls = 12
Let the number of black balls = x
Probability of getting black ball = Number of possible outcomes / Total number of outcomes
= x/12
If 6 more black balls are put in the box, the probability of drawing a black ball is now double what it was before,
Total number of balls = 12 + 6
Number of black balls = x + 6
Now,
2 × Probability of drawing black ball before = probability of drawing black ball
2 × Probability of drawing black ball before = Number of possible outcomes /Total number of outcomes
2(x/12) = (x + 6)/18
3x = x + 6
3x - x = 6
2x = 6
x = 3
Hence, previously, the number of black balls was 3.
Thus, the probability of getting a black ball initially was x/12 = 3/12 = 1/4.