a. Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. W
ID: 3274556 • Letter: A
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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