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At a monthly meeting, 2/5 of the attendees were males and [#permalink]
01 Jun 2008, 08:38
This post was BOOKMARKED
88% (02:27) correct
12% (01:13) wrong based on 89 sessions
At a monthly meeting, 2/5 of the attendees were males and 7/8 of the male attendees arrived on time. If 9/10 of the female attendees arrived on time, what fraction of the attendees at the monthly meeting did not arrive on time?
One can pick number or one can also do it without picking number depending on how comfortable one is with abstract calculations. For picking a number choose some thing that can be evenly divided by all the denominators given in the question. Solution by picking number Picking nunber = 100 Males = 100*2/5 = 40 Female = 100 - 40 = 60 Males Arrived on time = 40 * 7/8 = 35 Males Not Arrived on time = 40 - 35 = 5 Females Arrived on time = 60 * 9/10 = 54 Females Not Arrived on time = 60 - 54 = 6 Total later arrivals = 6 + 5 = 11 Ratio = 11/100
Solution by abstract method Total nunber = x Males = x*2/5 = 2x/5 Female = x - 2x/5 = 3x/5 Males Not Arrived on time = 2x/5 * (1-7/8) = x/20 Females Not Arrived on time = 3x/5 * (1-9/10) = 3x/50 Total later arrivals = x/20 + 3x/50 = 11x/100 Ratio = 11x/100/x = 11/100
Re: At a monthly meeting, 2/5 of the attendees were males and [#permalink]
02 Dec 2012, 12:00
2/5 of the attendees were males and 7/8 of the male attendees
How to pick nos? Here it is..
LCM of 5 and 8 is 40.. So pick no 40 for no of males..
so males=2/5 of total attendees= 40
7/8 of 40= 35 arrived on time
Hope it helps
Kudos if you like this approach..
I got the answer right because after I couldn't figure it out picking numbers, I tried to solve another way but I was wondering if you could help me figure it out with picking numbers approach.
How do we know to pick numbers for males and not total attendees? I picked 40 because it went into 5, 8, and 10. Then I figured out 2/5 of males of total attendees is 16 and 7/8 of 16 on time is 14 on time which means 2 not on time.
If 2/5 were males then that means 3/5 were females so 3/5 of the 40 is 24. 9/10 of that number is approximately 21 people which is approximately 3 females not on time.
Then that would be 3 females not on time + 2 males not on time = 5 / 40= 1/8
Re: At a monthly meeting, 2/5 of the attendees were males and
02 Dec 2012, 12:00