og 12 question 11 in ps

Expert replies

aerodan1: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Sat Jan 02, 2010 12:37 am

by aerodan1 » Thu Feb 11, 2010 10:02 pm

Hi all, I came across question 11 in the problem solving section of og 12 (page 153), and was a little confused about the explanation. the book says that the third root of 10 ^ -6 is 10 ^ -2. I suppose they divided -6 by 3 to get -2, but what is the logic behind that? thanks - dan

Like this post

Source: Beat The GMAT — Problem Solving | Thu Feb 11, 2010 10:02 pm

aerodan1: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Sat Jan 02, 2010 12:37 am

by aerodan1 » Thu Feb 11, 2010 10:20 pm

ha just answered my own question, realized that the real question to ask is "what raised to the third power equals 10 ^ -6?" and of course, 10^ -2 is the answer because when numbers with the same base are multiplied by one another, their exponents are simply added. yay me

Like this post

ajith: Legendary Member; Posts: 1275; Joined: Thu Sep 21, 2006 11:13 pmFollowed by: 2 members; Location: Arabian Sea; Thanked: 125 times

by ajith » Thu Feb 11, 2010 11:23 pm

aerodan1 wrote:Hi all, I came across question 11 in the problem solving section of og 12 (page 153), and was a little confused about the explanation. the book says that the third root of 10 ^ -6 is 10 ^ -2. I suppose they divided -6 by 3 to get -2, but what is the logic behind that? thanks - dan

Already discussed,

https://www.beatthegmat.com/cubes-og-12t ... 51426.html

Always borrow money from a pessimist, he doesn't expect to be paid back.

Like this post

sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Fri Feb 12, 2010 12:43 am

aerodan1 wrote:Hi all, I came across question 11 in the problem solving section of og 12 (page 153), and was a little confused about the explanation. the book says that the third root of 10 ^ -6 is 10 ^ -2. I suppose they divided -6 by 3 to get -2, but what is the logic behind that? thanks - dan

Third root means cube root, and cube root of x is given by x^(1/3). When x is 10^-6, its cube root is given by (10^-6)^(1/3) and since the laws of indices say that (a^m)^n = (a)^(m n), therefore (10^-6)^(1/3) = (10)^-6(1/3) = (10)^-2.

The mind is everything. What you think you become. -Lord Buddha

Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 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