BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

The average of x1, x2, x3, x4, x5 is m.

This topic has expert replies
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

[GMAT math practice question]

The average of x1, x2, x3, x4, x5 is m. What is the average of x1-a, x2-2a, x3-3a, x4-4a, x5-5a?

A. m
B. m - 1/2a
C. m - a
D. m - 3a
E. m - 3/2a
Source: — Problem Solving |

User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members
=>

Since m is the average of x1, x2, x3, x4, x5, we have m = (x1 + x2 + x3 + x4 + x5) / 5 or x1 + x2 + x3 + x4 + x5 = 5m.
Then the average of x1-a, x2-2a, x3-3a, x4-4a, x5-5a is
[(x1 - a) + (x2 - 2a) + (x3 - 3a) + (x4 - 4a) + (x5 - 5a)] / 5
= (x1 + x2 + x3 + x4 + x5 - 15a) / 5
= (x1 + x2 + x3 + x4 + x5 ) / 5 – 3a
= m – 3a

Therefore, D is the answer.
Answer: D