statistics
posted by Anonymous .
A spinner has equal regions numbered 1 through 21. What is the probability that the spinner will stop on an even number or a multiple of 3? (Points : 5)

Even numbers are 2, 4, 6, 8, 10, 12, 14, 16, 18, 20.
P(even) = 10/21
Multiples of 3 are 3, 6, 9, 12, 15, 18, 21.
Probability of either/or = sum of individual probabilities  common probabilities.