If the average (arithmetic mean) of a, b, and c is 40, what is the average (arithmetic mean) of (3a + 10), (3b +10), and (3c+10)?

A 90

B 120

C 130

D 150

Correct Answer: Option C

(a + b + c) / 3 = 40

or, a + b + c = 120

or, 3 * (a + b + c) = 120 * 3

or, 3a + 3b + 3c = 360

or, 3a + 3b + 3c + 30 = 360 + 30

or, (3a + 10) + (3b + 10) + (3c + 10) = 390

or, [(3a + 10) + (3b + 10) + (3c + 10)] / 3 = 390/3

= 130