Coins numbered 1-200 are placed in a hat. What is the probability that a coin chosen at random out of the hat is a multiple of 6 or 9?

Answer 1

multiples of 6:
6 12 18 .... 198 ---> 33 of them

multiples of 9
9 18 27 ... 198 ----> 22 of them

multiples of 18 , their LCM
18 36 ..198 ----> 11 of them

number of multiple of 6 OR 9 = 33 + 22 - 11 = 44

prob(multiple of 6 OR 9) = 44/200 = 11/50 or .22