I just took the Quant Foundation Assessment Test (Arithmetic): GRE Quant Foundation Assessment Test (Arithmetic)
The answer provided for the last question seems incorrect:
The last two cases can actually be NOT real numbers:
(negative Pi) → the square root of -pi is not a real number
-3/4 → the square root of -3/4 is not a real number.
or square root of (-1) which is equal to imaginary number i, which is not a real number.
So those two last cases are not encompassed by real numbers.
