Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE PS – The average (arithmetic mean) of 10, 30, and 50 is 5 more…

The average (arithmetic mean) of 10, 30, and 50 is 5 more…

Solution:

Let’s first determine the average of 10, 30, and 50, using the average formula.

average = sum/quantity

average = (10+30+50)/3

average = 90/3

average = 30

We can now rephrase the question to ask: “30 is 5 more than the average of 20, 40, and what value?” Let’s label the missing value as n and create an equation.

30 = (20+40+n)/3 + 5

25 = (20+40+n)/3

75 = 60 + n

15 = n

Answer: A