Question

Mrs. Smith’s students are trying to guess her age. She gives them 3 clues: (1) “My age is a factor of 60.” (2) “My age is a multiple of 5.” (3) “My age is more than 20 but less than 50.”
a
How old is Mrs. Smith?

Answer 1

30 yrs old




Explanation:

The factors of 60 are 1 and 60, 2 and 30, 3 and 20, 4 and 15, 5 and 12, and 6 and 10.

The next clue eliminates every number except 5, 10, 15, 20, 30, and 60.

5, 10, 15 are less than 20 and eliminated (60 is eliminated because it is more than 50).

20 is eliminated because it is not greater than itself and so Mrs. Smith must be 30.