Multiple Choice

Question

If the average of a and b equals the average of a, b, and c, then express c in terms of a and b.

 

a. a + b

b. 2(a+b)

c. a+b/2

d. a+b/3

Answer 1

I set up equation as follows, then solved for c:

(a + b) / 2 = (a + b + c) / 3; 3a + 3b = 2a + 2b + 2c; 3a -2a + 3b - 2b = 2c; 

a + b = 2c, so c = (a + b) / 2, so the answer is c (if the parentheses are used and not as shown in the multiple choice answers).