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Two musicians, Maria and Perry, work at independent constant

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Joined: 02 Aug 2009
Posts: 7960
Re: Two musicians, Maria and Perry, work at independent constant  [#permalink]

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New post 10 Apr 2018, 21:58
1
adkikani wrote:
Bunuel chetan2u

Quote:
Two musicians, Maria and Perry, work at independent constant rates to tune a warehouse full of instruments. If both musicians start at the same time and work at their normal rates, they will complete the job in 45 minutes. However, if Perry were to work at twice Maria’s rate, they would take only 20 minutes. How long would it take Perry, working alone at his normal rate, to tune the warehouse full of instruments?

A. 1 hr 20 min
B. 1 hr 45 min
C. 2 hr
D. 2 hr 20 min
E. 3 hr


Let the whole work be 180 units.

Is the highlighted text LCM of 45 and 20? If so, are not these mentioned as time units in main question stem?
How can I use smart numbers for two different variables wiz units and time?


Hi...

It is taken as LCM of 45 and 20....
You have to just realize that what ever value you take, it will have t o be divided by 45 and 20..

otherwise..
M and P together do in 45 min..
Twice M + M or 3 Ms do in 20 min, so M will do in \(20*3= 60\) min.

So if P joins M, it takes 45 min instead of 60 min..
But for 45 minutes M is also working, so work P does in 45 minutes saves 15 minutes of M work...
This means P takes \(\frac{45}{15}\) times M's time, so \(60*3=180\) min..
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Re: Two musicians, Maria and Perry, work at independent constant  [#permalink]

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New post 13 Apr 2019, 02:18
Easiest way:

3r*1/3=1 -> t=1h=60min

1*3/4+3x/4=1 -> 3+3x=4-> x=1/3 –> t=3h

done.
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Re: Two musicians, Maria and Perry, work at independent constant   [#permalink] 13 Apr 2019, 02:18

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