gmat prep 1 q

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by cramya » Sat Sep 20, 2008 8:22 am
(1/5)^m (1/4)^18 = 1/2*10^35 STEP1


{Since 1/4 = 1/2 ^ 2 and 10 = 2*5}

= 1/5^m 1/2^36 = 1/2^1 (1/2.5)^35 STEP 2

{
1) (ab)^m = a^m b ^m
2) a ^ m * a ^ n = a ^ m+n
3)I HAVE GROUPED 1/2 ^ 1 AND 1/2 ^ 35 AS 1/2 ^ 36)
}

=1/5 ^ m * 1/2 ^ 36 = (1/2) ^ 36 * (1/5)^35 STEP3

Therefore m = 35

Whats the OA?

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by smallsorrow » Sat Sep 20, 2008 8:57 am
you are correct: 35 is the OA

thank you!!

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by stop@800 » Sat Sep 20, 2008 9:01 am
Easy way:

Denom is 2^36 and 5^m
and we need 2. (10)^35 = 2. (5 * 2)^35

hence m = 35