If a = 4b, what percent of 2a is 2b?

Expert replies

Previous Topic Next Topic

VJesus12: Legendary Member; Posts: 2276; Joined: Sat Oct 14, 2017 6:10 amFollowed by: 3 members

by VJesus12 » Mon May 14, 2018 1:31 am

Timer

00:00

Answers

Stats

Difficulty—

If a = 4b, what percent of 2a is 2b?

(A) 10%
(B) 20%
(C) 25%
(D) 26%
(E) 40%

The OA is the option C.

I am confused here. Could anyone help me here? Please. I'd really appreciate it.

Like this post

Source: Beat The GMAT — Problem Solving | Mon May 14, 2018 1:31 am

GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Mon May 14, 2018 2:42 am

VJesus12 wrote:If a = 4b, what percent of 2a is 2b?

(A) 10%
(B) 20%
(C) 25%
(D) 26%
(E) 40%

Let b=1, implying that a = 4b = 4*1 = 4.
What percent of 2a is 2b?
2b/2a = b/a = 1/4 = 25%.

The correct answer is C.

Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3

Like this post

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Mon May 14, 2018 5:53 am

VJesus12 wrote:If a = 4b, what percent of 2a is 2b?

(A) 10%
(B) 20%
(C) 25%
(D) 26%
(E) 40%

The OA is the option C.

I am confused here. Could anyone help me here? Please. I'd really appreciate it.

I would have used the same approach that Mitch used.
However, here's an algebraic approach:

If a = 4b, then 2a = 8b

What percent of 2a is 2b?
We can rewrite as: 2b/2a = what percent?
Or, we can write: 2b/8b = what percent?
Simplify: 1/4 = what percent?

Since 1/4 = 25%, the correct answer is C

Cheers.
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Like this post

Jeff@TargetTestPrep: GMAT Instructor; Posts: 1462; Joined: Thu Apr 09, 2015 9:34 amFollowed by: 22 members; Location: New York, NY; Thanked: 39 times

by Jeff@TargetTestPrep » Tue May 15, 2018 3:37 pm

VJesus12 wrote:If a = 4b, what percent of 2a is 2b?

(A) 10%
(B) 20%
(C) 25%
(D) 26%
(E) 40%

Simplifying, we have:

b/a = 1/4

2b/2a = 1/4 as well, which is 25%.

Answer: C

Jeffrey Miller
Head of GMAT Instruction
[email protected]

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review