a. Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. W

Question

a. Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

b. A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

c. In a box, there are 8 red, 7 blue and 6 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green?

d. What is the probability of getting a sum 9 from two throws of a dice?

e.Three unbiased coins are tossed. What is the probability of getting at most two heads?

Please explain

Explanation / Answer

Solution:-

a) The probability that the ticket drawn has a number which is a multiple of 3 or 5 is 0.45.

Total number of tickets = 20

Number of multiples of 3 = 6 = (3, 6, 9, 12, 15, 18)

Number of multiples of 5 = 4 = (5, 10, 15, 20)

Number of multiples of 3 or 5 = 9 = (3, 5, 6, 9, 10, 12, 15, 18, 20)

The probability that the ticket drawn has a number which is a multiple of 3 or 5 = 9/20 = 0.45

b) The probability that none of the balls drawn is blue is 0.4762.

Number of ways of drawing 2 balls = 7C2 = 21

Number of ways of not drawing  blue balls = 5C2 = 10

The probability that none of the balls drawn is blue = 10/21 = 0.4762

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