GMAT Practice Question: If x>y and y>z, which of the following represents the greatest number?
Question
If x>y and y>z, which of the following represents the greatest number?
- x-z
- x-y
- y-x
- z-y
- z-x
Topics: inequalities, comparisons
Solution
Step 1
We first note the given inequalities.
x>y y>z
Step 2
We apply \textbf{\text{"Chain Rule for Inequalities"}} to combine them.
x>z
Step 3
We subtract y from both sides of x>y to find the sign of x-y.
x-y>0
Step 4
We subtract z from both sides of x>z to find the sign of x-z.
x-z>0
Step 5
We express x-z as the sum of the positive differences x-y and y-z.
x-z=(x-y)+(y-z)
Step 6
Since both x-y and y-z are positive, their sum x-z is the greatest among the listed expressions.
Answer
x-z
