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John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 00:44
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Competition Mode Question John can eat x doughnuts in y minutes. If Chen can eat doughnuts three times as fast as John, how many doughnuts will John and Chen eat in an hour? (A) \(15*\frac{4x}{4}\) (B) \(60*\frac{3x}{y}\) (C) \(15*\frac{16x}{y}\) (D) \(60*\frac{x}{y}\) (E) \(60*\frac{x}{3y}\) Are You Up For the Challenge: 700 Level Questions
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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 01:20
John can eat x doughnuts in y minutes. Chen eats three time as fast as John i.e. Chen can eat 3x doughnuts in y minutes. i.e. Chen and John can eat (x+3x) = 4x donughnuts in y minutes i.e. in 1 hour (60 minutes) they can eat (4x/y)*60 = 240x/y doughnuts every hour i.e. 15(16x/y) doughnuts every hour Answer: Option C
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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 01:25
In Y mins, John eat doughnuts = X so, in 1 min, John will eat = \(\frac{X}{Y}\) Similarly, in 1 min, Chen will eat = \(\frac{3X}{Y}\) ... (eats Three times faster). Together they will eat in 1 min = \(\frac{X}{Y}+\frac{3X}{Y}\) = \(\frac{4X}{Y}\) So, in 1 hour (60 mins), they will eat  \(\frac{4X}{Y} * 60\) = \(240 * \frac{4X}{Y}\) which is equivalent to our option 'C'  \(15*\frac{16X}{Y}\)
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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 03:30
John can eat (x/y) doughnuts in 1 minute. In an hour, he can eat 60*(x/y) doughnuts.
Chen can eat 3*(x/y) doughnuts in 1 minute. In an hour, he can eat 180*(x/y) doughnuts.
Together, they eat (60+180)*(x/y) = 240*(x/y) = 15*16*(x/y) doughnuts in an hour
FINAL ANSWER IS (C)
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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 04:34
Quote: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three times as fast as John, how many doughnuts will John and Chen eat in an hour?
(A) 15∗4x/4 (B) 60∗3x/y (C) 15∗16x/y (D) 60∗x/y (E) 60∗x/3y r=td john rate: x/y d/min chen rate: 3x/y d/min j+c 1 hr: 60min * (x/y+3x/y) = 60(4x/y) = 240x/y = 15(16x/y) Ans (C)



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 05:20
John can eat x doughnuts in y minutes > Number of doughnuts John can eat in 1 minute = \(\frac{x}{y}\)
Chen can eat doughnuts three times as fast as John > Number of doughnuts Chen can eat in 1 minute = \(3*\frac{x}{y} = \frac{3x}{y}\)
Number of doughnuts John & Chen can eat in 1 minute together = \(\frac{x}{y} + \frac{3x}{y} = \frac{4x}{y}\)
In 1 hour = 60 minutes = \(60*\frac{4x}{y} = 15*\frac{16x}{y}\)
Option C



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 07:52
John's rate: r=x/y Chen's rate: r=3x/y Combined rate: 4x/y
Solution: YummyDonuts = 60 * (4x/y) = 15 * (16x/y) < Recognizing that these two are the same is the tricky part I think.
Answer: C



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 09:58
John: x doughnuts in y minutes —> \(\frac{x}{y}\) —doughnuts per minute
Chen : \(3(\frac{x}{y})\) Together in an hour: —> \((\frac{x}{y}+ 3*\frac{x}{y})*60 = 240(\frac{x}{y})\)
Only answer choice C matches this answer ( \(15*\frac{16x}{y})\)
The answer is C
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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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24 Jan 2020, 20:51
John can eat x doughnuts in y minutes. Rate of John = (x/y) min
If Chen can eat doughnuts three times as fast as John Rate of Chen = 3x/y min
Using RT=W equation Combined rate is 4x/y min
In 1 hour they will eat 4x/y * 60 = 240x/y
Checking the options C is correct



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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25 Jan 2020, 01:23
Quote: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three times as fast as John, how many doughnuts will John and Chen eat in an hour?
(A) \(15∗\frac{4x}{4}\)
(B) \(60∗\frac{3x}{y}\)
(C) \(15∗\frac{16x}{y}\)
(D) \(60∗\frac{x}{y}\)
(E) \(60∗\frac{x}{3y}\) John can eat x doughnuts in y minutes => The number of doughnuts John can eat in an hour is \(x*\frac{60}{y}\) Chen can eat doughnuts three times as fast as John => The number of doughnuts Chen can eat in an hour is \(3x*\frac{60}{y}\) => The number of doughnuts John and Chen will eat in an hour is \(4x*\frac{60}{y} = 15∗\frac{16x}{y}\) ==>>> Choice C



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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25 Jan 2020, 09:08
Ans: C
John in 1 min= x/y Chen in 1 min=3x/y
so in 60 min= 60(x/y + 3x/y)=240 x/y= 15 16x/y



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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25 Jan 2020, 09:16
2 methods; method 1 :
Rate of John ; x/y and Rate of Chen ; 3x/y
in 60 mins they would be able to eat ; 4x/y * 60 = 240*x/y or say 15 * 16 x/y IMO C
method 2 let rate of John be x=5 donuts per y= 30 mins ; i.e 10 donuts per hour now rate of Chen would be 30 donuts per hour ; total donuts eaten John + chen ; 40 substitute x & y in 15 * 16 * 5/ 30 ; IMO C;
John can eat x doughnuts in y minutes. If Chen can eat doughnuts three times as fast as John, how many doughnuts will John and Chen eat in an hour?



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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25 Jan 2020, 09:34
John eats x/y donuts / minute Chen eats 3x/y donuts /minute Together they eat 4x/y donuts/minute = 60 * 4x/y = 15* 16x/y donuts / hour
IMO C
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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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25 Jan 2020, 14:51
In y minutes, John can eat x doughnuts. Chen can eat 3x in y minutes. Hence Chen and John can eat a total of 4x doughnuts in y minutes. We are to determine how many doughnuts Chen and John can eat in 60 minutes. With the above information, we can reduce this question to a simple case of ratio and proportions. y minutes : 4x 60 minutes : z z=4x * 60/y = (15 * 16x)/y
The answer is C.



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Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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26 Jan 2020, 09:08
John can eat doughnuts per minute = x/y Chen can eat doughnuts per minute =3x/y, (As Chen can eat doughnuts three times as fast as John) John and Chen eat doughnuts in one minute = x/y +3x/y = 4x/y John and Chen eat doughnuts in an hour (60 minutes) = 4x*60/y = 240x/y = 15*16/y (15*16 =240)(C)




Re: John can eat x doughnuts in y minutes. If Chen can eat doughnuts three
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