If \(2^x=3,\) then which of the following must be true?

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If \(2^x=3,\) then which of the following must be true?

A. \(1\frac13<x<1\frac12\)

B. \(1\frac12<x<1\frac23\)

C. \(1\frac23<x<1\frac34\)

D. \(1\frac34<x<1\frac56\)

E. \(1\frac56<x<2\)

Answer: B

Source: GMAT Club Tests

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Gmat_mission wrote:
Tue Nov 10, 2020 7:28 am
If \(2^x=3,\) then which of the following must be true?

A. \(1\frac13<x<1\frac12\)

B. \(1\frac12<x<1\frac23\)

C. \(1\frac23<x<1\frac34\)

D. \(1\frac34<x<1\frac56\)

E. \(1\frac56<x<2\)

Answer: B

Source: GMAT Club Tests
Solution:

Since 2^(3/2) = 2 * 2^(1/2) = 2√2 ≈ 2.8, we see that x > 3/2 since 2^x = 3 > 2.8.

Since 2^(5/3) = 2 * 2^(2/3) = 2∛4 ≈ 3.2, we see that x < 5/3 since 2^x = 3 < 3.2.

Therefore, we see that 3/2 < x < 5/3 or 1½ < x 1⅔.

Answer: B

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