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agni_h1: Junior | Next Rank: 30 Posts; Posts: 14; Joined: Tue Jun 08, 2010 1:19 pm

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by agni_h1 » Sat May 14, 2011 9:12 pm

1) If (1/5)^m*(1/4)^18 = 1/2*(10)^35, m?
a. 18
b. 17
c. 21
d. 35
e. 3

Answer given is 35.I am not very sure of the approach,I am somehow getting only -35.

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Source: Beat The GMAT — Problem Solving | Sat May 14, 2011 9:12 pm

smackmartine: Legendary Member; Posts: 516; Joined: Fri Jul 31, 2009 3:22 pm; Thanked: 112 times; Followed by:13 members

by smackmartine » Sat May 14, 2011 9:29 pm

(1/5)^m*(1/4)^18 = 1/2*(1/10)^35
(1/5)^m * (1/2)^36 = (1/2)^36 *(1/5)^35

(1/5)^m = (1/5)^35

bases are same so m=35

I guess you are getting confused by 1/5, so lets convert the base to 5 . But you need to change the sign of the powers too.

(5)^-m = (5)^-35
-m= -35
m=35 (same answer)

Last edited by smackmartine on Sat May 14, 2011 10:55 pm, edited 1 time in total.

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bblast: Legendary Member; Posts: 1077; Joined: Mon Dec 13, 2010 1:44 am; Thanked: 118 times; Followed by:33 members; GMAT Score:710