Let A=2^50, B=3^30, and C=5^20.

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Let A=2^50, B=3^30, and C=5^20.

by Max@Math Revolution » Mon Feb 19, 2018 11:33 pm
[GMAT math practice question]

$$LetA\ =2^{50},B=3^{30},\ and\ C=5^{20}$$ . Which of the following is true?

A. A < B < C
B. A < C < B
C. C < A < B
D. B < C < A
E. C < B < A

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by Max@Math Revolution » Thu Feb 22, 2018 1:04 am
=>

If we wish to compare these numbers, we need to either make their bases the same or make their exponents the same. In this case, it is easiest to make all exponents the same as follows:
A=2^50 = (2^5)^10 = 32^10
B=3^30 = (3^3)^10 = 27^10
C=5^20 = (5^2)^10 = 25^10

Since 32 > 27 > 25, we must have A > B > C.

Therefore, the answer is E.

Answer: E