Is the average (arithmetic mean) of the numbers x, y, and z greater than z?
Assume: (x + y + z)/3 > z
x + y + z > 3z
x + y > 2z
If the value of x + y is greater than 2z, then the average of x, y, and z is greater than z.
Statement 1: z - x < y - z
x + y > z + z
x + y > 2z
Hence, statement 1 is sufficient to answer the question.
Statement 2: x < z < y
From this statement, you cannot say whether x + y > 2z or not. Hence, statement 2 is not sufficient to answer the question.
The correct option is A.