Math questions from 2007 ADA

[20090900]

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I need some help with a couple questions from the 2007 ADA QR section. Help would be most appreciated.

38) Jill has six different books. She will select one book on Monday and a different one to read on Wednesday. In how many ways can Jill select two different books?
--> I really suck at knowing when to use combinations/permutations

35) What is the maximum number of 3-inch squares (squares that are three inches on a side) that can be cut from a sheet of tin 19 x 23 inches?
--> My answer: (19x23) / (3x3) = 48.55...but the answer says 42???

32) If y = (x+2) / (x-3), which of the following represents x?
--> Don't really know/understand how to do this...I tried re-arranging/solving for x but didn't work out....

13) 10 is to 2y as 25x is to....
--->wtf???

5) At a certain convention the ratio of men to women was 3 to 8. If there were 352 people there, how many were men?
--> My answer: (3/8) x 352 = 132...but the answer says 96???

Last question: My biggest problem on QR was time...I've done DAT destroyer math and MATH destroyer but I know they're harder than the actual DAT therefore doing a timed test for those isn't really representative of the real DAT. Is there any practice you guys can suggest for practicing time? aka what resource has difficult most similar to the QR section of the DAT?

Thanks!

 

[ikecarus]

38) n!/(n-2)! = 6!/4! = 30

35) The way you've set up the equation assumes that you can rearrange the tin sheet. However, you need to figure out how many squares will fit on each side of the tin sheet without "going over". 3 goes into 19 six times so there will be six columns of 3-inch squares. Then 3 goes into 23 seven times so there will be seven rows of 3-inch squares. 6 X 7 = 42. The rest of the tin sheet is a border and cannot be "made" into 3 inch squares.

32) You can definitely re-arrange this:
y = (x+2) / (x-3)
y(x - 3) = x + 2
xy - 3y = x + 2
xy - x = 3y + 2
x (y - 1) = 3y + 2
x = (3y + 2) / (y - 1)

13) Set up the proportions and set the unknown part of the ratio as "z"
10/2y = 25x/z
Cross multiply:
50xy = 10z
z = 5xy (your answer)

5) To set up this problem...
3x + 8x = 352
11x = 352
x = 32
So now to find the number of men at the convention... multiply x by 3.
3(32) = 96

Hope this helps. 🙂

Also, to answer your question about timing... it would actually be really helpful for you to take some timed Math Destroyer tests, especially since you've already done it once and can now re-do it to see if you've really understood the concepts behind each question. I started out with an adequate foundation of math (though I hadn't taken math in three years) but I took all of the Math Destroyer tests timed and forced myself to finish under pressure so now I can finish the "easier" math tests with ~15-20 minutes leftover to check for mistakes. But if you're struggling to finish non-Destroyer math tests, then I would really focus on understanding how to do the problems so that you can quickly identify and set up equations when you come across a problem. (disclaimer: I haven't actually taken the DAT yet, (I will be taking it in... 3 days!) but I've finished Math Destroyer and taken all the full-length Kaplan tests and done well on their QR section (average ~24), barring dumb mistakes haha. Also I've taken both 2007 and 2009 ADA tests with about the same average for QR)

 

[20090900]

Awesome thank-you SO much for the help. I didn't expect one person to answer all the questions haha. I also really appreciate the advice. Good luck on your test!

 

[ikecarus]

You're more than welcome! I took the 2007 test yesterday so all of those QR problems were still fresh in my mind. And thanks! Good luck to you too. 🙂