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Tired Interns

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Tired Interns

by nik08 » Sun Sep 07, 2008 2:02 am
At a certain hospital, 75% of the interns receive fewer than 6 hours of sleep and report feeling tired during their shifts. At the same time, 70% of the interns who receive 6 or more hours of sleep report no feelings of tiredness. If 80% of the interns receive fewer than 6 hours of sleep, what percent of the interns report no feelings of tiredness during their shifts?

A. 6
B. 14
C. 19
D. 20
E. 81

Can someone help?
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Re: Tired Interns

by parallel_chase » Sun Sep 07, 2008 2:26 am
nik08 wrote:At a certain hospital, 75% of the interns receive fewer than 6 hours of sleep and report feeling tired during their shifts. At the same time, 70% of the interns who receive 6 or more hours of sleep report no feelings of tiredness. If 80% of the interns receive fewer than 6 hours of sleep, what percent of the interns report no feelings of tiredness during their shifts?

A. 6
B. 14
C. 19
D. 20
E. 81

Can someone help?
Lets there be 100 interns.

75 sleep less than 6 hours
25 sleep more than 6 hours

70% of 25 = interns sleep more than 6 hours and report no feeling of tiredness

70/100 * 25 = 17.5

if 80 people sleep less then 6 hours then.

17.5/75 = x/80

17.5 * 80 = 75*x

x=18.6

the answer should be 19.

Hope this helps.
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Re: Tired Interns

by Stockmoose16 » Tue Sep 09, 2008 4:41 pm
parallel_chase wrote:
nik08 wrote:At a certain hospital, 75% of the interns receive fewer than 6 hours of sleep and report feeling tired during their shifts. At the same time, 70% of the interns who receive 6 or more hours of sleep report no feelings of tiredness. If 80% of the interns receive fewer than 6 hours of sleep, what percent of the interns report no feelings of tiredness during their shifts?

A. 6
B. 14
C. 19
D. 20
E. 81

Can someone help?
Lets there be 100 interns.

75 sleep less than 6 hours
25 sleep more than 6 hours

70% of 25 = interns sleep more than 6 hours and report no feeling of tiredness

70/100 * 25 = 17.5

if 80 people sleep less then 6 hours then.

17.5/75 = x/80

17.5 * 80 = 75*x

x=18.6

the answer should be 19.

Hope this helps.

Another way you could solve it:

Imagine there are 100 interns:

80 < 6 hrs sleep
20 > 6 hrs sleep

75 < 6 hrs sleep & feel tired (which means 80-75= 5 are NOT tired)
Out of the 20 who get > 6 hrs sleep, 70% are Not tired. 20*.7= 14 NOT TIRED

Thus, 14+5 = 19% NOT TIRED
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by cramya » Fri Sep 19, 2008 8:48 pm
Make a table for problems like these. Its a whole lot easier to work with.
Since percents are involved work with 100 as total (easiest)

In the excel sheet attached we get to 19.

5 not tired in <6 category
14 not tired in the 6 or more category
Attachments
probsol.xls
(13.5 KiB) Downloaded 181 times
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