The average (arithmetic mean) of 3a + 4 and another number is 2a. What is the average of the other number and a ?

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

Redeem

This topic has expert replies

Post new topic Post Reply

Previous Topic Next Topic

BTGModeratorVI: Legendary Member; Posts: 1223; Joined: Sat Feb 15, 2020 2:23 pm; Followed by:1 members

The average (arithmetic mean) of 3a + 4 and another number is 2a. What is the average of the other number and a ?

by BTGModeratorVI » Tue Dec 15, 2020 6:58 am

Timer

00:00

Your Answer

Global Stats

The average (arithmetic mean) of 3a + 4 and another number is 2a. What is the average of the other number and a ?

A. 2a
B. a - 4
C. a - 2
D. a + 2
E. a + 4

Answer: C
Source: Kaplan

Quote

Source: Beat The GMAT — Problem Solving | Tue Dec 15, 2020 6:58 am

GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

Re: The average (arithmetic mean) of 3a + 4 and another number is 2a. What is the average of the other number and a ?

by Scott@TargetTestPrep » Thu Mar 16, 2023 6:02 pm

BTGModeratorVI wrote: ↑
Tue Dec 15, 2020 6:58 am
The average (arithmetic mean) of 3a + 4 and another number is 2a. What is the average of the other number and a ?

A. 2a
B. a - 4
C. a - 2
D. a + 2
E. a + 4

Answer: C
Source: Kaplan

We can let n = the average of the other number and create the following equation:
(3a + 4 + n)/2 = 2a

3a + 4 + n = 4a

4 + n = a

The average of the other number and a is:

(n + 4 + n)/2 = (2n + 4)/2 = n + 2

Since n = a - 4, we can say:

n + 2 = a - 4 + 2 = a - 2

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]