A certain hall contains two cuckoo clocks. If the first clock chirps 20 times per hour and the second clock chirps 10

[BTGmoderatorDC]

A certain hall contains two cuckoo clocks. If the first clock chirps 20 times per hour and the second clock chirps 10 times per hour, and both clocks begin chirping at 1:15 PM, at what time will the first clock have chirped three times as many times as the second clock can per hour?

A. 1:24 PM
B. 2:05 PM
C. 2:30 PM
D. 2:45 PM
E. 4:15 PM



OA D

Source: Veritas Prep

[Jay@ManhattanReview]

A certain hall contains two cuckoo clocks. If the first clock chirps 20 times per hour and the second clock chirps 10 times per hour, and both clocks begin chirping at 1:15 PM, at what time will the first clock have chirped three times as many times as the second clock can per hour?

A. 1:24 PM
B. 2:05 PM
C. 2:30 PM
D. 2:45 PM
E. 4:15 PM

OA D

Source: Veritas Prep

The wording of the question is tricky.

Let's first understand the meaning of the phrase, "... the second clock can per hour".

The phrase means the number of times the second clock can chirp in an hour. We already know the second clock chirps to times in an hour.

Thus, we want a time when the first would have chirped 3*10 = 30 times.

Since the first clock chirps 20 times in an hour, it will take 30/20 = 1.5 hours for it to chirp 30 times. Thus, the times when it would happen after 1.15 would be 1.15 pm + 1.5 hours = 2.45 pm.

The correct answer: D

Hope this helps!

-Jay
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[swerve]

A certain hall contains two cuckoo clocks. If the first clock chirps 20 times per hour and the second clock chirps 10 times per hour, and both clocks begin chirping at 1:15 PM, at what time will the first clock have chirped three times as many times as the second clock can per hour?

A. 1:24 PM
B. 2:05 PM
C. 2:30 PM
D. 2:45 PM
E. 4:15 PM



OA D

Source: Veritas Prep

"At what time will the first clock have chirped three times as many times as the second clock CAN (!!) per hour?"

It is easy to interpret the question as "what time has clock A chirped 3 times more than clock B?" - do some calculations and come up with E

But, We basically want to know when the first clock has chirped 3∗10=30times3∗10=30times

Clock A chirps 20 times each hour \(\Longrightarrow\) 1 time each 3 min \(\Longrightarrow\) 30 times in 90 min

1:15PM + 90min = 2:45PM

Therefore, the correct answer is __D__

[Scott@TargetTestPrep]

A certain hall contains two cuckoo clocks. If the first clock chirps 20 times per hour and the second clock chirps 10 times per hour, and both clocks begin chirping at 1:15 PM, at what time will the first clock have chirped three times as many times as the second clock can per hour?

A. 1:24 PM
B. 2:05 PM
C. 2:30 PM
D. 2:45 PM
E. 4:15 PM



OA D

Source: Veritas Prep

Since the second clock can chirp 10 times per hour and we want the first clock to chirp 3 times as many, we want the first clock to chirp 30 times. Since the first clock chirps 20 times per hour (60 minutes), it will chirp 30 times in 60/20 x 30 = 3 x 30 = 90 minutes. Therefore, at 1:15 PM + 90 minutes = 2:45 PM, the first clock will have chirped three times as many times as the second clock can per hour.

Answer: D