If 3 ＜ x ＜ 100，for how many values of x/3 is the square of a prime number?
A.2
B.3
C.4
D.5
E.9
A.2
B.3
C.4
D.5
E.9
Let's begin by listing some prime numbers: 2, 3, 5, 7, 11, 13 . . .GmatKiss wrote:If 3 ＜ x ＜ 100，for how many values of x/3 is the square of a prime number?
A.2
B.3
C.4
D.5
E.9
So, some squares of prime numbers: 2^2, 3^2, 5^2, 7^2, 11^2 . . .
When we evaluate each one, we get 4, 9, 25, 49, 121,...
- For x/3 to equal 4, x must equal 12
- For x/3 to equal 9, x must equal 27
- For x/3 to equal 25, x must equal 75
- For x/3 to equal 49, x must equal a number greater than 100. Since we're told that x<100, we can stop and conclude that there are 3 values of x such that x/3 is the square of a prime number
So, the answer is B
Cheers,
Brent
