Question

X is a number from the set [3,5,6] and y is a number from the set [4,7,8,9]. If xz/y is an integer and z is a positive integer, what is the lowest possible value of z?
A) 1
B) 2
C) 3
D) 4
Plzz help!

Answer 1

The smallest possible value of z is the denominator of the reduced fraction x/y. We note the prime factors of the members of set y are

... 2², 7, 2³, 3²

so if there are any even members of set x, the fraction can be reduced to something divided by 2. The number 6 in set x is even, so we have

... 6z/4 = 6·2/4 = 3 (an integer) when z=2

The lowest possible value of z is ...

... B) 2