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

Redeem

Exponents

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Mon Sep 14, 2009 5:07 pm
Thanked: 1 times

Exponents

by manochsa » Mon Nov 16, 2009 8:34 pm
Could someone please identify the fastest approach to solving the following:

(0.8)^-5/(0.4)^-4

A. 3/32
B. 5/64
C. 1/2
D. 1
E. 2

Thanks!
Top
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 91
Joined: Tue Aug 25, 2009 7:50 am
Location: Washington DC
Thanked: 2 times
GMAT Score:600

by ershovici » Tue Nov 17, 2009 1:32 am
the answer is B.

(0.8)^-5/(0.4)^-4 = (8/10)^-5/(4/10)^-4 = (10/8)^5/(10/4)^4 = 10^5*4^4/8^5*10^4 = 4^4*10/8^5 = 2^8*10/2^15 = 10/2^7 = 5*2/2^7 = 5/2^6 = 5/64
Top
Post new topic Post Reply
• Page 1 of 1