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#### Tired Interns (CAT 2)

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 Post subject: Tired Interns (CAT 2)  Posted: Sun Jul 01, 2012 4:17 am
 Students

Posts: 7
 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 6B 14C 19D 20E 81===================Please note the first line (without a 'who').At a certain hospital, 75% of the interns receive fewer than 6 hours of sleep and report feeling tired during their shifts.And also the second line (contains a 'who').At the same time, 70% of the interns who receive 6 or more hours of sleep report no feelings of tiredness. First line conveys the meaning that 75% of total interns receive fewer than 6 hours of sleep. This meaning contrasts the final line..If 80% of the interns receive fewer than 6 hours of sleep..therefore problem is absurd without a 'who' in first line. The explanation to the question assume that 75% interns mentioned in first are the ones who receive fewer than 6 hours of sleep.The meaning may be obvious for some, but it confused me during CAT 2. which wasted some of my time, also i did not get this question right.

 Post subject: Re: Tired Interns (CAT 2)  Posted: Tue Jul 03, 2012 8:03 am
 ManhattanGMAT Staff

Posts: 4404
Location: Southwest Airlines, seat 21C
 no. take a closer look at what the 75% represents. you can't just stop reading in the middle of a sentence.. :) _________________Tim SandersManhattan GMAT Instructor

 Post subject: Re: Tired Interns (CAT 2)  Posted: Tue Jul 03, 2012 12:12 pm
 Students

Posts: 7
 tim wrote:no. take a closer look at what the 75% represents. you can't just stop reading in the middle of a sentence.. :)Sir,elaboration of the meaning will help.

 Post subject: Re: Tired Interns (CAT 2)  Posted: Thu Jul 05, 2012 4:32 am
 ManhattanGMAT Staff

Posts: 4404
Location: Southwest Airlines, seat 21C
 taking a closer look at this one yourself would help. what does the 75% represent, and what does the 80% represent? you seem to think they represent the same things, which they don't. take a closer look.. _________________Tim SandersManhattan GMAT Instructor

 Post subject: Re: Tired Interns (CAT 2)  Posted: Tue Aug 14, 2012 4:11 pm
 Forum Guests

Posts: 125
 Is the answer A for this one? This is how I solved it. Let the total population of interns be x. Then, interns who receive less than 6 hours of sleep=.75x.Interns who receive more than 6 hours of sleep=.25x.70% of these interns complaint of tiredness. Now, if 80% of the students receive less than 6 hours of sleep, then .30*.20x=.06X do not complaint. Am I right in this question. Somehow I don't seem to be using the first part of the question which makes me doubt my answer.

 Post subject: Re: Tired Interns (CAT 2)  Posted: Tue Aug 14, 2012 4:14 pm
 Forum Guests

Posts: 125
 I have read through the question multiple times and the only difference I can find is the second statement involving the quantity 80% has an IF and is thus the hypothetical situation for which we have to calculate data. But if so, the statement mentioning that 75% of the interns receive lesser than 6 hours of sleep is not used.

 Post subject: Re: Tired Interns (CAT 2)  Posted: Mon Aug 20, 2012 5:30 pm
 Forum Guests

Posts: 7
 Has anyone found an answer to this question... i cannot seem to understand what the ask is based on the information given.

 Post subject: Re: Tired Interns (CAT 2)  Posted: Mon Aug 20, 2012 5:41 pm
 Forum Guests

Posts: 125
 Yup, I finally got it. 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? P(people who receive lesser and 6 hours of sleep and are tired)= 0.75*X--------1)P(people who receive fewer than 6 hours of sleep)=.80*X----2)Therefore, P(people who receive more than 6 hours of sleep)=0.20*X--------3)P(receive more than 6 hours of sleep and report no tiredness)=0.70*0.20*x----4)Now consider the total number of people are 100Thus the values become P(people who receive lesser and 6 hours of sleep and are tired)= 75--------1)P(people who receive fewer than 6 hours of sleep)=80 ----2)Therefore, P(people who receive more than 6 hours of sleep)=20 --------3)P(receive more than 6 hours of sleep and report no tiredness)=14----4)Hence, from 1 and 2) 5 people receive less than 6 hours of sleep and don't complain of tiredness and combining 4 with it answer is 19.C.

 Post subject: Re: Tired Interns (CAT 2)  Posted: Tue Aug 21, 2012 1:28 pm
 ManhattanGMAT Staff

Posts: 4404
Location: Southwest Airlines, seat 21C
 sounds good. let us know if there are any further questions on this one.. _________________Tim SandersManhattan GMAT Instructor

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