Probability - Online Test
Q1. A person throws successively with a pair of dice. The chance that he throws 9 before he throws 7 is
Answer : Option D
Explaination / Solution:
No Explaination.
Q2. Two cards are drawn at random and without replacement from a pack of 52 playing cards. Find the probability that both the cards are black.
Answer : Option D
Explaination / Solution:
Required probability : P(BB) = P(B) X P(B/B) ……………{B means black card} .
Q3. A box of oranges is inspected by examining three randomly selected oranges drawn without replacement. If all the three oranges are good, the box is approved for sale, otherwise, it is rejected. Find the probability that a box containing 15 oranges out of which 12 are good and 3 are bad ones will be approved for sale.
Answer : Option D
Explaination / Solution:
Total oranges = 15., Good Oranges = 12. Therefore , Required Probability =.
Q4.
Given that the events A and B are such that P(A) =, P (A ∪ B) = and P(B) = p. Find p if A and B are mutually exclusive
Answer : Option A
Explaination / Solution:
Since A and B are mutually exclusive events.,
Q5.
Given that the events A and B are such that P(A) =, P (A ∪ B) = and P(B) = p. Find p if they independent.
Answer : Option D
Explaination / Solution:
Q6. Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4. Find P(A ∩ B)
Answer : Option B
Explaination / Solution:
Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4
Q7. Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4.Find P(A ∪ B)
Answer : Option C
Explaination / Solution:
Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4
Since the events are independent, P(AB) = P(A).P(B)
ThereforeP(AB) = P(A) + P(B)
= 0.3 + 0.4 - 0.12 = 0.58
Q8. Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4.Find P (A|B)
Answer : Option C
Explaination / Solution:
Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4 P(A/B)=P(A)=0.3.
Q9. Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4. Find P(B|A).
Answer : Option A
Explaination / Solution:
Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4. P(B/A)=P(B)=0.4
Q10. If A and B are two events such that P(A) = ¼ , P(B) = ½ and , Find P(not A and not B ) .
Answer : Option A
Explaination / Solution:
Since A and B are independent events .
not A and not B are also independent events .
not A and not B are also independent events .
