Consecutive Exponents Question

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

srd: Newbie | Next Rank: 10 Posts; Posts: 2; Joined: Thu May 07, 2015 4:15 pm

Consecutive Exponents Question

by srd » Thu May 07, 2015 4:48 pm

Hi, having a hard time with this problem from a Veritas Prep practice test. Does anyone have any insight into how to solve it? The answer explanation did not make sense to me.

The correct answer was E.

Thanks in advance.

Quote

Source: Beat The GMAT — Problem Solving | Thu May 07, 2015 4:48 pm

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

by GMATGuruNY » Thu May 07, 2015 5:51 pm

E-C = 9Â¹Â³ - 9Â¹Â¹ = 9Â¹Â¹(9Â² - 1) = 9Â¹Â¹(80).

Since D-A = 3 spaces on the number line and E-C = 2 spaces on the number line, we get the following ratio:
(D-A)/(E-C) = 3/2
D-A = (3/2)(E-C).

Thus:
D-A = (3/2)(E-C) = (3/2)(9Â¹Â¹)(80) = 120(9Â¹Â¹).

The correct answer is E.

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

Quote

GMAT/MBA Expert

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