Question

An integer is chosen at random between 1 and 100. Find the probability that it is

1) divisible by 8.

2) not divisible by 8.

Answer 1

S = {2, 3 ..., 99}

n(S) = 98

1) A: Getting an integer divisible by 8. 

A = {8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96}

n(A) = 12

${\displaystyle P\left(A\right)=\frac{n\left(A\right)}{n\left(s\right)}=\frac{12}{98} =0.1224}$

2) B: Getting an integer not divisible by 8

P(B) = 1 -">−- Probability of getting integer divisible by 8

P(B) = 1 -">−- P(A) = 1 - 0.1224 = 0.8756