Probability
- A box contains 3 white and 2 red balls. If we draw one ball and ball and without replacing the first ball. The probability of drawing red ball in the second drawn is ?
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Total balls in the box = 5
Second red ball can be drawn in two ways
Case I. First ball is white and second ball is red.
Its probability = 3/5.2/4 = 6/20 = 3/10
Case II: First ball is red and second ball is red
Its probability = 2/5.1/4 = 2/20 = 1/10Correct Option: B
Total balls in the box = 5
Second red ball can be drawn in two ways
Case I. First ball is white and second ball is red.
Its probability = 3/5.2/4 = 6/20 = 3/10
Case II: First ball is red and second ball is red
Its probability = 2/5.1/4 = 2/20 = 1/10
Hence, reqd. probability
= 3/10 + 1/10 = 4/10 = 2/5
- Three mangoes and three apples are kept in a box. if two fruits are chosen at random. find the probability that one is a mango and the other is an apple.
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Total number of ways
= n(s) = 6c2 = 15
Favorable number of ways
= n(E) = 3C1 x 3C1= 9Correct Option: B
Total number of ways
= n(s) = 6c2 = 15
Favorable number of ways
= n(E) = 3C1 x 3C1= 9
∴ Required probability = 9/15 = 3/5
- The probability that a man will be alive for 10 more years is 1/4 and the probability that his wife will alive for 10 more years is 1/3 .The probability that none of them will be alive for 10 more years, is
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Required probability = P(A) x P(B)
= (1 - 1/4) x (1 - 1/3)Correct Option: B
Required probability = P(A) x P(B)
= (1 - 1/4) x (1 - 1/3) = 3/4 x 2/3 = 1/2
- In a lottery 10000 tickets are sold and ten prizes are awarded. What is the probability of not getting a prize, if you buy one ticket ?
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Total lottery tickets = 10000
Total prize in the lottery = 10
∴ Probability getting a prize
= 10/10000 = 1/1000Correct Option: C
Total lottery tickets = 10000
Total prize in the lottery = 10
∴ Probability getting a prize
= 10/10000 = 1/1000
Now, probability of not getting a prize
= 1 - probability of getting a prize
= 1 - (1/1000)
= 999/1000
- Tow persons A and B appear in an interview for two vacancies. If the probabilities of their selections are 1/3 and 1/6 respectively, then the probability that none of them is selected, is
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Required probability = P (A) x p (B)
= (1- 1/4) x (1- 1/6)Correct Option: A
Required probability = P (A) x p (B)
= (1- 1/4) x (1- 1/6) = (3/4) x (5/6)
= 5/8