Today’s question of the day gives you a chance to practice your data sufficiency skills. Click here for the answer and explanation.
Note that we cannot be sure that y = z since x may be 0. So we are left with two possibilities
x = 0 or y = z.
We still don’t know whether x is 0. So, if x is 0, then z may or may not be equal to 4. If x ≠ 0, z = y = 2. This statement alone is insufficient.
The correct answer would be among B/C/E.
x is a positive integer means that x ≠ 0 and y = z. However, we don`t know the value of either y or z. This statement alone is insufficient.
The correct answer would be between C/E.
Statement (1 & 2)
From statement (2), we know that x ≠ 0 and y = z, and from statement (1), we know that y = 2; hence, we know that z = 2 ≠ 4, a unique answer.
Correct choice is C.