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If Biff can shape 3 surfboards in 50 minutes, how many

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by Vincen » Tue Nov 28, 2017 6:26 am
If Biff can shape 3 surfboards in 50 minutes, how many surfboards can he shape in 5 hours?

(A) 16
(B) 17
(C) 18
(D) 19
(E) 20

The OA is C .

Should I make the conversion between hours and minutes? I am confused. Experts, may you help me here?
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by GMATGuruNY » Tue Nov 28, 2017 6:41 am
Vincen wrote:If Biff can shape 3 surfboards in 50 minutes, how many surfboards can he shape in 5 hours?

(A) 16
(B) 17
(C) 18
(D) 19
(E) 20
50 minutes = 5/6 hour.
Since 3 surfboards are shaped in 5/6 hour, the rate = w/t = 3/(5/6) = (3)(6/5) = 18/5 surfboards per hour.
Since Biff's rate = 18/5 surfboards per hour, and his time = 5 hours, the number of surfboards shaped = rt = (18/5)(5) = 18.

The correct answer is C.
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by Brent@GMATPrepNow » Tue Nov 28, 2017 6:56 am
Vincen wrote:If Biff can shape 3 surfboards in 50 minutes, how many surfboards can he shape in 5 hours?

(A) 16
(B) 17
(C) 18
(D) 19
(E) 20
We can also solve this question be applying some number sense

NOTE: 5 hours = 300 minutes

Given: Biff can shape 3 surfboards in 50 minutes.
So: Biff can shape 6 surfboards in 100 minutes [If we DOUBLE the amount of time Biff has, we DOUBLE his output]
Likewise, Biff can shape 9 surfboards in 150 minutes. [If we TRIPLE the amount of time Biff has, we TRIPLE his output]
.
.
.
Biff can shape 18 surfboards in 300 minutes [If multiply Biff's work time by 10, we multiply his output by 10]
Answer: C

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Brent
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by Scott@TargetTestPrep » Wed Jan 03, 2018 3:59 pm
Vincen wrote:If Biff can shape 3 surfboards in 50 minutes, how many surfboards can he shape in 5 hours?

(A) 16
(B) 17
(C) 18
(D) 19
(E) 20
Note that 5 hours = 5 x 60 = 300 minutes. We can set up a ratio:

3/50 = x/300

50x = 900

x = 18 surfboards in 5 hours

Answer: C

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