Question

An integer is chosen at random between 1 and 100. Find the probability that it is :
(i) divisible by 8.
(ii) not divisible by 8.

Answer 1

Total numbers are 2, 3, 4, ....., 99
(i) Let E be the event of getting a number divisible by 8.
E = {8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96}
= 12
P(E) = $\frac{Favourableoutcomes}{Totaloutcomes}$
$=\frac{12}{98}=0.1224$
(ii) Let E' be the event of getting a number not divisible by 8.
Then, P(E') = 1 - P(E)
= 1 - 0.1224
= 0.8756