OG - #D14

[mww7786]

Here is where I get frustrated. I've picked up the skills and understanding from MGMAT and PR, but the diagnostic questions seem to take the material into an entirely new relm. How is it possible to make this leap?

D14 - I applied all the MGMAT strategies

Of the 84 parents who attended a meeting at a school, 35 volunteered to supervise children during a school picnic and 11 volunteered both to supervise the children during the picnic and volunteered to bring refreshments. 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 parents brought refreshments?

choices: a. 25 b 36c. 38 d. 42 e. 45

Step 1) Use Venn Diagram only for sets of 3
so use double set matrix for overlapping sets

Step 2) catagories: supervise/ not supervise Bring Refreshments/ not bring refreshments

Step 3) so, Total parents bringing Refreshments = 1.5 X

Step 4) (I gained more insight as I typed this out)

Are we saying that the reason Total refresh =36 B

is because: 1.5(24) = 36 Therefore, Not Refresh/ Not supervise = 24: Refresh/Not supervise=24

So Total Refresh: 36 + Not Refreshed = 48 is 84 total

The way I did this seems a little convoluted. Please shed some light. Thanks so much. :cool:

[StaceyKoprince]

A little tough to show this one since I can't draw the double-set matrix. Draw one yourself and fill in as I explain. Not sure how you calculated 24, so I showed the whole thing below. :)

Categories are:
S = supervise
NS = not supervise
R = refreshements
NR = not refreshments

Any of the above abbreviations preceded by a T means the total for that group.

Overall total is 84. T-S = 35 and SR = 11. Therefore, SNR = 24 and T-NS = 49.
Label NSNR with an x and T-R with 1.5x.
Label NSR with 49-x.

For R, we now have 11 + (49-x) = 1.5x. Solve to get x = 24. If x = 24, then 1.5x = 36.

All of your manipulations are just based on your ability to add the various rows and columns in a double-set matrix.