What is the probability of 1-20 of getting even or odd numbers, a prime number or 1, a multiple of 3 or 7.

Question

Using a number generator what is the probability of a prime number or 1, even or odd and a multiple of 3 or 7. The number generator picks numbers 1-20.

Answer 1

Primes between 1 and 20: 1,2,3,5,7,11,13,17,19. That's 9 in all so probability is 9/20=45%.

Evens: 2,4,6,8,10,12,14,16,18,20. That's 10, probability 10/20=50%, the same as odds.

Multiples of 3 or 7: 3,6,7,9,12,14,15,18. That's 8, probability 8/20=40%.