Math
posted by Kristen on .
Coins numbered 1200 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?

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