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 ?
-
View Hint View Answer Discuss in Forum
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.
-
View Hint View Answer Discuss in Forum
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
- Out of 13 applicants for a job, there are 5 women and 8 men It is desired to select 2 persons for the job, The probability that atleast one of the selected persons will be a woman, is
-
View Hint View Answer Discuss in Forum
Total ways = 13c2
Favourable number ways of selecting men only = 8c2
∴ Probability of selecting no woman
= 8c2 / 13c2
= 14/39Correct Option: A
Total ways = 13c2
Favourable number ways of selecting men only = 8c2
∴ Probability of selecting no woman
= 8c2 / 13c2
= 14/39
∴ Probability of selecting at least one woman
= 1 - (14 / 39)
= 25 / 39
- A and B are two events such that P(A) = 0.3 and P ( A∪B) = 0.8. If A and B are independent, then P (B) is
-
View Hint View Answer Discuss in Forum
Let P(B) = x
Given, P(A∪B) = 0.8 and P(A) = 0.3
⇒ P(A) + P(B) - P(A∩B) = 0.8
⇒ P(A) + P(B) - P(A) P(B) = 0.8 {∵A and B are independent}Correct Option: E
Let P(B) = x
Given, P(A∪B) = 0.8 and P(A) = 0.3
⇒ P(A) + P(B) - P(A∩B) = 0.8
⇒ P(A) + P(B) - P(A) P(B) = 0.8 {∵A and B are independent}
⇒ 0.3 + x - 0.3x = 0.8
⇒ 0.7x = 0.5
∴ x = 5/7
- Five coins are tossed at a time. Then, the probability of obtaining at least one tail is
-
View Hint View Answer Discuss in Forum
Total events = n (s) = 25 = 32
n(E) of getting heads = 1
p(E) = 1/32
∴ n(E) = 1 - p(E)Correct Option: A
Total events = n (s) = 25 = 32
n(E) of getting heads = 1
p(E) = 1/32
∴ n(E) = 1 - p(E) = 1 - 1/32 = 31/32