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chdn20: Newbie | Next Rank: 10 Posts; Posts: 7; Joined: Sun Dec 27, 2009 6:02 am

by chdn20 » Sun May 16, 2010 5:30 am

Of the 84 parents who attended a meeting at a school, 35 volunteered to supervise children during the school picnic and 11 volunteered both to supervise children during the picnic and to bring refreshments to the picnic. If the number of parents who volunteered to bring refreshments was 1.5 times the number of parents who neither volunteered to supervise children during the picnic nor volunteered to bring refreshments, how many of the parents volunteered to bring refreshments?

A) 25
B) 36
C) 38
D) 42
E) 45

Any sight would be great. I have been trying to solve the problem using the group 1+group 2+ neither + both, but its not working.

Can you solve using a variation of this:

24+11+1.5x+x=84?

Thanks,

Chris

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Source: Beat The GMAT — Problem Solving | Sun May 16, 2010 5:30 am

clock60: Legendary Member; Posts: 759; Joined: Mon Apr 26, 2010 10:15 amFollowed by: 3 members; Thanked: 85 times

by clock60 » Sun May 16, 2010 5:49 am

chdn20 wrote:Of the 84 parents who attended a meeting at a school, 35 volunteered to supervise children during the school picnic and 11 volunteered both to supervise children during the picnic and to bring refreshments to the picnic. If the number of parents who volunteered to bring refreshments was 1.5 times the number of parents who neither volunteered to supervise children during the picnic nor volunteered to bring refreshments, how many of the parents volunteered to bring refreshments?

A) 25
B) 36
C) 38
D) 42
E) 45

Any sight would be great. I have been trying to solve the problem using the group 1+group 2+ neither + both, but its not working.

Can you solve using a variation of this:

24+11+1.5x+x=84?

Thanks,

Chris

many ways are possible one of them is double matrix

___________ supervise ____ not supervise______ total
_bring refresh _11___________ ________________1.5 x
not bring refr__24___________ x______________ (24 +x)
__ total_____ 35___________49______________84

1.5x+(24+x)=84
x=24
24*1,5=36
so my answer B ( some figures in the table are useless don`t pay attention)

let me know OA?

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chdn20: Newbie | Next Rank: 10 Posts; Posts: 7; Joined: Sun Dec 27, 2009 6:02 am

by chdn20 » Sun May 16, 2010 5:54 am

Thanks for the help. Why would you not at the 11 people?

Thanks

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clock60: Legendary Member; Posts: 759; Joined: Mon Apr 26, 2010 10:15 amFollowed by: 3 members; Thanked: 85 times

by clock60 » Sun May 16, 2010 7:48 am

chdn20 wrote:Thanks for the help. Why would you not at the 11 people?

Thanks

the problem asks
how many of the parents volunteered to bring refreshments?
11 includes both who bring refreshments and supervise, but we need those who supervise and bring +not supervise but bring

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harshavardhanc: Legendary Member; Posts: 526; Joined: Sat Feb 21, 2009 11:47 pm; Location: India; Thanked: 68 times; GMAT Score:680

by harshavardhanc » Sun May 16, 2010 7:50 am

chdn20 wrote: Any sight would be great. I have been trying to solve the problem using the group 1+group 2+ neither + both, but its not working.

Can you solve using a variation of this:

24+11+1.5x+x=84?

Thanks,

Chris

you were very close!

the equation will become : 24 + x + 2/3 x = 84 , where x is the number of people who bring refreshments.

you'll get the answer as 36.

Regards,
Harsha

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indiantiger: Master | Next Rank: 500 Posts; Posts: 362; Joined: Fri Oct 02, 2009 4:18 amFollowed by: 1 member; Thanked: 26 times

by indiantiger » Sun May 16, 2010 5:06 pm

I agree, you were very close:

I used this formula
Group1+ Group2 -Both + Neither = Total

35+3/2*N-11+N = 84

this becomes

84-24 = 5/2*N
60*2/5 = N
N = 24

Parents bringing refreshments = 3/2*24 = 36(B)

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frank1: Legendary Member; Posts: 537; Joined: Fri Jan 22, 2010 10:06 pmFollowed by: 1 member; Thanked: 14 times

by frank1 » Sun May 16, 2010 7:08 pm

i think one motive of asking question like this is suck up the time.....
one has to collect lots of info here (and if not is hasty s/he will easily mis-collect the info) and at wrost case they have answer matching wrong information collection
i used this
84-x=35+1.5x-11

i.e x=24
1.5x=36

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