CON ED?

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CON ED?

by smclean23 » Wed Jul 30, 2008 4:03 pm
A certain electric-company plan offers customers reduced rates for electricity used between 8 p.m. and 8 a.m. weekdays and 24 hours a day Saturdays and Sundays. Under this plan, the reduced rates apply to
what fraction of a week?
(A) 1/2
(B) 5/8
(C) 9/14
(D) 16/21
(E) 9/10



Answer is C
Source: — Problem Solving |

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by Vignesh.4384 » Wed Jul 30, 2008 8:25 pm
IMO C.


Request : smclean23 please put the answers in the spoiler.

Thanks,
vignesh

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by parallel_chase » Thu Jul 31, 2008 1:20 am
8 am to 8 pm - 12hrs * 5 weekdays =60

24 hrs on Sat & Sun = 48 hrs

60+48 = 108

Total hours in a week = 24*7=168


fraction = 108/168 =9/14

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by augusto » Thu Jul 31, 2008 6:57 am
An easy way answer this question is to consider one week as 14 'half days'

So the discount will apply for 5 half days during the weekdays, and for 4 half days during the weekend.

so it's 9/14.


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Augusto

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by malolakrupa » Thu Jul 31, 2008 7:06 am
Sat and Sunday - 24 * 2
Mon - Fri - 12*5

Total Hours in a week - 24 * 7

Hence the fraction is (24* 2 + 12* 5) / 24*7 = (12 * 9 ) / 24* 7 = 9/14

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by smclean23 » Thu Jul 31, 2008 9:22 am
My method was to actually count out the number of hours. I guess I read too much into the question.

It says obviously states the weekend, which is 48 hours...FINE..got that part!

Now 8pm to 8 am on weekdays....doesn't that mean Monday nite at 8pm to Tuesday morning at 8am..Tuesday nite at 8pm to Wednesday morning...Wednesday nite to Thursday morning...Thursday nite to Friday morning then 8pm Friday nite to 12:00 on Saturday morning.....All of this gives me 100/168...

Is this reading too much into it?

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by pepeprepa » Thu Jul 31, 2008 9:25 am
I don't really see the problem with your method, it is faster than 2 minutes and you are right so it's ok.

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by smclean23 » Thu Jul 31, 2008 9:26 am
Never mind I got the answer. Using my logic, I forgot to add the 12 to 8am on Monday morning which makes it 108/168...Thanks!

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by malolakrupa » Thu Jul 31, 2008 9:29 am
Good point . If you were to do it that way then the answer has to be 11/21 , which is not in the list of answers given.

How do we get that

Sat and Sun - 48
Mon - Fri - 12 + 12 + 12 + 4 = 40

Hence the answer = 88/(24*7) =11/21.

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by malolakrupa » Thu Jul 31, 2008 9:33 am
Good point . If you were to do it that way then the answer has to be 11/21 , which is not in the list of answers given.

How do we get that

Sat and Sun - 48
Mon - Fri - 12 + 12 + 12 + 4 = 40

Hence the answer = 88/(24*7) =11/21.