SAT question

Discussion in 'General' started by E n i g m a, Jan 23, 2010.

  1. #1 E n i g m a, Jan 23, 2010
    Last edited by a moderator: Jan 23, 2010
    I'm looking at a 2010 SAT prep book and one of the practice questions is as follows:
    17. A dress is selling for $100 after a 20 percent discount. What was the original selling price?

    (A) $200
    (B) $125
    (C) $120
    (D) $80
    (E) $75

    The obvious answer to me is C because it is 20 percent more.
    But no the book says that the answer is B. How can this be?
    B is 125, 25% more than the discount price.


     
  2. Its B. 125$
    10% of 125$ is 12.50
    so 20% is 25$

    125-25=100
     
  3. #3 Misc, Jan 23, 2010
    Last edited by a moderator: Jan 23, 2010
    ratios ratios ratios
     
  4. I'm sorry but I don't understand, it's like inorder to solve the problem you have to already know the answer. The question is asking for 20% more than 100 which in my book is 120.
     
  5. #5 Lucien Lachance, Jan 23, 2010
    Last edited by a moderator: Jan 23, 2010
    You are going to do so poorly on the math section.

    80 100
    -- = --
    100 x

    You cross multiply. 80 times x, 100 times 100.

    80x=10,000
    10,000/80=125
     

  6. Heres teh equation.

    x= unknown original price

    x(.80)=$100

    You multiply by .80 because 20% is being taken off, or in other words ure paying 80% of the full price.

    100/.80 = 125$
     
  7. very simple, take 20% off of all of the answers, which one gives you 100?
     
  8. a different way lol

    100=80% of original price
    if you use ratios to solve 100:x=80:100

    x=125
     
  9. Oh yeah, that's a faster way.
     
  10. It helps me to think about it as a fraction, rather then a percent. So we know that 20% is equal to 1/5. If you answered C, the discount would actually be 1/6 b/c 6*20=120. The answer is B or 125 b/c 5*25=125, therefore 20% (or 1/5) of 125 is 25. B is the correct response. I hope this helps, the questions can be tricky.
     
  11. Nope.

    0.8x=100
    x=$125

    The answer checks out:

    80% x ($125)=$100
     
  12. this...
     

  13. The question isn't asking you to take 20% of 100, it's asking you what you would need to take 20% from to get 100.
     
  14. That is the slowest way. Considering you have roughly 30 seconds for each question, time is far too important for slow methods like that.
     
  15. Calculator > GrassCity.
     

  16. It's called algebra
     
    • Like Like x 1
  17. So you're saying, even if you didn't know how to do it any other way, it would take you more than 30 seconds to crunch out 2 equations, considering you should be able to eliminate A, D, and E almost instantaneously?
     
  18. really those choices are obvious as fuck he had to choose from either 120 or 125...
     
  19. this worked for me and i did pretty well in read + math
     
  20. #20 Highskore, Jan 23, 2010
    Last edited by a moderator: Jan 23, 2010
    Grasscity > Everything

    Divide by zero my friend.

    EDIT: I actually looked at the problem and realized instantly it was B without seeing the options. Very simple problem IMO. I've taken the SAT's before and did ok on the math section but I'm actually retaking the SAT's just to bump up what I can tomorrow morning at 7:45.
     

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