BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Tired VS Not tired problem

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Senior | Next Rank: 100 Posts
Posts: 80
Joined: Sat Sep 15, 2012 1:07 am
Thanked: 1 times
Followed by:1 members

Tired VS Not tired problem

by AIM TO CRACK GMAT » Mon Jan 14, 2013 7:05 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?

i) 6 ii)14 iii) 19 iv) 20 v)81
Top
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 23
Joined: Wed Feb 23, 2011 7:32 am
Thanked: 8 times
Followed by:2 members
GMAT Score:740

by vkb001 » Mon Jan 14, 2013 4:49 pm
If T is the total number of interns,

Number of interns with less than 6 hours of sleep and feeling tired = 0.75*T (given)
Number of interns with less than 6 hours of sleep = 0.8*T (given)

Therefore, number of interns with less than 6 hours of sleep and NOT feeling tired = (0.8 - 0.75)*T = 0.05*T

Number of interns with 6 or more hours of sleep = T - 0.8*T = 0.2*T
Number of interns with 6 or more hours of sleep and NOT feeling tired = 0.7*(0.2*T) = 0.14*T
Number of interns with 6 or more hours of sleep and feeling tired = 0.2*T - 0.14*T = 0.06*T

Answer: The number of interns that report no tiredness = 0.14*T + 0.05*T = 0.19*T = 19% of the total
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 645
Joined: Mon Jul 26, 2010 12:42 pm
Location: US
Thanked: 527 times
Followed by:227 members

by e-GMAT » Tue Jan 15, 2013 12:16 am
AIM TO CRACK GMAT 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?

i) 6 ii)14 iii) 19 iv) 20 v)81
Hi,

Pl. look at the image. Hope it is self explanatory.

Image

Answer would be 19%.

-Shalabh
Top
Senior | Next Rank: 100 Posts
Posts: 45
Joined: Fri Apr 06, 2012 5:28 am
Thanked: 3 times
Followed by:2 members
GMAT Score:500

by BTG14 » Thu Jan 17, 2013 3:45 am
iii) 19%. Correct answer.

Nicely explained by e-gmat.
Top
User avatar
Senior | Next Rank: 100 Posts
Posts: 80
Joined: Sat Sep 15, 2012 1:07 am
Thanked: 1 times
Followed by:1 members

by AIM TO CRACK GMAT » Thu Jan 17, 2013 6:38 am
e-GMAT wrote:
AIM TO CRACK GMAT 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?

i) 6 ii)14 iii) 19 iv) 20 v)81
Hi,

Pl. look at the image. Hope it is self explanatory.

Image

Answer would be 19%.



Thank u sooo much... this is another easy method or may b easier to undastand since its in a tabular form...thank u sooo much!!! Apreciate it

-Shalabh
Top
Post new topic Post Reply
• Page 1 of 1