Answer
Probability = $\frac{32}{100}$ = $\frac{8}{25}$
Work Step by Step
Numbers divisible by 5 = [100/5] = 20 ([ ] represent greatest integer function)
Number divisible by 7 = [100/7] = 14
Number divisible by both 5 and 7 = [100/35] = 2
Using set theory we know number divisible by either 5 or 7 = 20 + 14 - 2 = 32
Total number = 100
Probability = $\frac{32}{100}$ = $\frac{8}{25}$
