Power Prep software problem

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mpaudena: Senior | Next Rank: 100 Posts; Posts: 80; Joined: Wed Jun 04, 2008 1:16 pm; Thanked: 3 times

by mpaudena » Fri Sep 18, 2009 9:35 am

If 5^21 * 4^11 = 2 * 10^n what is the value of n?

A) 11

B) 21

C) 22

D) 23

E) 32

Please tell me answer and how you arrive at the answer. Thanks.

Source: Beat The GMAT — Problem Solving | Fri Sep 18, 2009 9:35 am

sagaragr: Newbie | Next Rank: 10 Posts; Posts: 3; Joined: Thu Jul 30, 2009 9:59 pm; Thanked: 1 times

by sagaragr » Fri Sep 18, 2009 2:28 pm

you can rewrite the equation like this..

(5^(21))*(4^(11))

= (5^(21))*((2^2)^11)

= (5^(21))*(2^(22))

= (5*2)^(21) * 2

= 10^(21) * 2

n = 21

mpaudena: Senior | Next Rank: 100 Posts; Posts: 80; Joined: Wed Jun 04, 2008 1:16 pm; Thanked: 3 times

by mpaudena » Sat Sep 19, 2009 4:51 am

Thanks bud.

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