Question

How many positive integers less than or equal to 100 are divisible by 2, 4 or 5?

(a) 12.3

(b) 87.2

(c) 45.3

(d) 78.2

I have been asked this question during an online interview.

My enquiry is from Addition Theorem on Probability in chapter Discrete Probability of Discrete Mathematics

Answer 1

Right answer is (d) 78.2

To elaborate: To count the number of integers = \(\frac{100}{2} + \frac{100}{4} + \frac{100}{5} – \frac{100}{8} – \frac{100}{20} + \frac{100}{100}\)

= 50 + 25 + 20 – 12.8 – 5 + 1 = 78.2.