Algebra

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

BTGmoderatorRO: Moderator; Posts: 772; Joined: Wed Aug 30, 2017 6:29 pm; Followed by:6 members

Algebra

by BTGmoderatorRO » Sat Oct 28, 2017 4:08 am

John is one year older than three times Linda's age. If their ages currently add up to 33 years, then how old will John be in 4 years?
A. 12
B. 25
C. 29
D. 30
E. 37
OA is c
How can I go about getting the correct answer here? Thanks

Quote

Source: Beat The GMAT — Problem Solving | Sat Oct 28, 2017 4:08 am

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pm; Location: Palo Alto, CA; Thanked: 2867 times; Followed by:511 members; GMAT Score:800

by [email protected] » Sat Oct 28, 2017 11:13 am

Hi Roland2rule,

We're told that John is one year older than three times Linda's age, and the sum of their ages is 33 years. We're asked for John's age in 4 YEARS.

There are a couple of different ways to approach this question - since the answer choices are relatively small, you can actually use some 'brute force' arithmetic and get the correct answer without too much trouble:

IF...
Linda is 1, then John is 4 and the total is 5
Linda is 2, then John is 7 and the total is 9
Linda is 3, then John is 10 and the total is 13

Notice how the total age increases by 4 years each time... getting from a total of 13 years to a total of 33 years shouldn't be too tough (it's just 5 more 'steps'):
Linda is 8, then John is 25 and the total is 33

Thus, in 4 years, John will be 25+4 = 29

Final Answer: C

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

Quote

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

by Scott@TargetTestPrep » Tue Nov 12, 2019 7:17 pm

BTGmoderatorRO wrote:John is one year older than three times Linda's age. If their ages currently add up to 33 years, then how old will John be in 4 years?
A. 12
B. 25
C. 29
D. 30
E. 37
OA is c
How can I go about getting the correct answer here? Thanks

We can let John's current age = J and Linda's current age = L and create the following equations:

J = 1 + 3L

and

J + L = 33

Thus:

1 + 3L + L = 33

4L = 32

L = 8, so J = 25. So, in 4 years, John will be 29.

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]