Bunuel
If a + b = 5c, then which of the following represents the average (arithmetic mean) of a, b, and c, in terms of c?
A. 3c + 1
B. 2c
C. 5c
D. c/3
E. 3c/2
We can solve questions like this (VIACs - Variables in the Answer Choices) by using algebra (as sashiim20 has done), or by using the
INPUT-OUTPUT approach.
Let's use the INPUT-OUTPUT approach
First find numbers that meet the given condition: a + b = 5c
One option is
a = 0, b = 5 and
c = 1Given these values, the average of a, b and c = (
0 + 5 + 1)/3 =
2So, when we INPUT
a = 0, b = 5 and
c = 1, the OUTPUT (the average of a, b and c) is
2In this question, we care only about the value of c.
So, let's take the answer choices and plug in
c = 1, and see which one yields an OUTPUT of
2A. 3(
1)+ 1 =
4 Not a match. ELIMINATE
B. 2(
1) =
2 a match. KEEP
C. 5(
1) =
5 Not a match. ELIMINATE
D.
c = 1/3 =
1/3 Not a match. ELIMINATE
E. 3(
1)/2 =
3/2 Not a match. ELIMINATE
Answer: