Probability – Exercise – 1

36. A bag contains 3 red, 4 white and 5 blue balls. All balls are different. Two balls are drawn at random. The probability that they are of different colour, is :

(a) 47/66
(b) 10/33
(c) 5/22
(d) none of these

37. In order to get atleast once a head with probability ≥0.9, the number of times a coin needs to be tossed, is :

(a) 3
(b) 4
(c) 5
(d) none of these

38. Odds 8 to 5 against a person who is 40 years old living till he is 70 and 4 to 3 against another person now 50 till he will be living 80. Probability that one of them will be alive next 30 years, is :

(a) 59/91
(b) 44/91
(c) 51/91
(d) 32/91

39. In a certain town, 40% of the people have brown hair, 25% have brown eyes and 15% have both brown hair and brown eyes. If a person selected at random from the town, has brown hair, the probability that he also has brown eyes, is :

(a) 1/5
(b) 3/8
(c) 1/3
(d) 2/3

40. A six faced dice is biased that it is twice as likely to show an even number as an odd number when thrown. It is thrown twice. The probability that the sum of two numbers thrown is even, is :

(a) 1/12
(b) 1/6
(c) 1/3
(d) 2/3

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