If Naomi can mow 12.5% of a field every hour, then she can mow 25 identical fields in how many hours?

[BTGmoderatorDC]

If Naomi can mow 12.5% of a field every hour, then she can mow 25 identical fields in how many hours?

A. 8
B. 10
C. 25
D. 100
E. 200


OA E

Source: Princeton Review

[swerve]

If Naomi can mow 12.5% of a field every hour, then she can mow 25 identical fields in how many hours?

A. 8
B. 10
C. 25
D. 100
E. 200


OA E

Source: Princeton Review

Since \(12.5\% = \dfrac{1}{8},\) let each field \(= 8\) units.

Since Naomi mows \(\dfrac{1}{8}\) of an \(8\)-unit field each hour, her hourly rate \(= \dfrac{1}{8}\cdot (8) = 1\) unit per hour.

Since each field \(= 8\) units, a job composed of \(25\) fields \(= 25 \cdot 8 = 200\) units.

Since the hourly rate \(= 1\) unit per hour, the time to complete a \(25\)-field job composed of \(200\) units \(=\dfrac{\text{work}}{\text{rate}}=\dfrac{200}{1}=200\) hours

Hope this helps!

[Brent@GMATPrepNow]

If Naomi can mow 12.5% of a field every hour, then she can mow 25 identical fields in how many hours?

A. 8
B. 10
C. 25
D. 100
E. 200


OA E

Source: Princeton Review

12.5% = 12.5/100 = 1/8, which means Naomi's RATE is 1/8 of a field per hour.
We want to determine the time it will take for her to mow 25 identical fields.

time = output/rate = 25/(1/8)
= (25)(8/1)
= 200

Answer: E