Probability
 What is the probability that a number selected from the numbers 1, 2, 3, 4, 5....16 is a prime number ?

 1/16
 5/8
 3/8
 7/16

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S = {1, 2, 3, ......16}
E = {2, 3, 5, 7, 11, 13}
∴ P(E) = n(E)/n(S) = 6/16= 3/8Correct Option: C
S = {1, 2, 3, ......16}
E = {2, 3, 5, 7, 11, 13}
∴ P(E) = n(E)/n(S) = 6/16= 3/8
 An urn contains 9 red, 7 white and 4 black balls. A ball is drawn at random. What is the probability that the ball drawn is not red ?

 1/11
 9/20
 2/11
 11/20

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P (red) = 9 / (9 + 7 + 4) = 9/20
Correct Option: D
P (red) = 9 / (9 + 7 + 4) = 9/20
∴ P(notred) = (1  9/20) = 11/20
 In a lottery there are 20 prizes and 15 blanks. What is the probability of getting prize ?

 1/10
 2/5
 4/7
 2/7

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P (getting a prize ) = 20 / (20 + 15 ) = 20 / 35 = 4/7
Correct Option: C
P (getting a prize ) = 20 / (20 + 15 ) = 20 / 35 = 4/7
 The odds in favour of an event are 3 : 5. The probability of occurrence of the event is ?

 3/5
 3/8
 1/3
 1/5

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Number of cases favourable of E = 3
Total Number of cases = (3 + 5 ) = 8
∴ P(E) = 3/8Correct Option: B
Number of cases favourable of E = 3
Total Number of cases = (3 + 5 ) = 8
∴ P(E) = 3/8
 The probability of getting heads in both trials when a balanced coin is tossed twice will be ?

 1/4
 1/2
 1
 3/4

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Probability of getting head in one trail = 1/2
∴ Reqd Probability of getting heads in both the trails = 1/2 x 1/2 = 1/4Correct Option: A
Probability of getting head in one trail = 1/2
∴ Reqd Probability of getting heads in both the trails = 1/2 x 1/2 = 1/4