Question

Andrea's locker combination only contains composite numbers. Which of the following could be her locker combination?

a. 42, 60, 15

b. 17, 45, 90

c. 75, 34, 13

d. 21, 31, 51

Answer 1

(a)

Explanation:

Prime numbers only have 2 factors, 1 and the number itself.

Numbers which have other factors are composite.

(a) are all composite numbers

(b) 17 is a prime number

(c) 13 is a prime number

(d) 31 is a prime number

The locker combination must therefore be (a)