Probability a multiple of 4
= 4, 8, 12, 16, 20, 24, 28, 32, 36, 40
= 10/40
= 1/4
Probability a multiple of 5
= 5, 10, 15, 25, 30, 35
= 6/40
= 3/20
Probability(Selection a multiple of 4 or 5)
= 1/4 + 3/20
= 8/20
Note: Do not include multiples of 5 that intersect with multiples of 4, this will cause the probability to repeat.
e.g. 20 is a multiple of 4 and 5
∴ Only include this number once.
