During a special promotion, a certain filling station is offering a 10% discount on gas purchased after the first 10 gallons. If Kim purchased 20 gallons of gas and Isabella purchased 25 gallons of gas, then Isabella's total per-gallon discount is what percent of Kim's total per-gallon discount?
OA: D
Please help cant figure out how to go about the sum
Princeton review problem
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- eaakbari
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It easy if you plug in a value for your per gallon cost. Say its 1$.
Now for Kim
10 + 0.9 *1*10 = 19 $.
Hence per gallon discount is 19/20$ = 0.95
Similarly for Isabella
10 + 0.9*1*15 = 23.5 = 47/2 $
Hence per gallon discount is 47/50 $ = 0.94
Per gallon discount for kim = 0.5
Per gallon discount for Isabella= 0.6
0.5/0.6*100 = 120%
P.S you forgot to mention choices
Now for Kim
10 + 0.9 *1*10 = 19 $.
Hence per gallon discount is 19/20$ = 0.95
Similarly for Isabella
10 + 0.9*1*15 = 23.5 = 47/2 $
Hence per gallon discount is 47/50 $ = 0.94
Per gallon discount for kim = 0.5
Per gallon discount for Isabella= 0.6
0.5/0.6*100 = 120%
P.S you forgot to mention choices
Last edited by eaakbari on Sun Apr 04, 2010 11:51 pm, edited 1 time in total.
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I am getting the answer as 120%
consider cost per gallon as $100
Kim spend= 100*10 + 90*10 =1900-->cost per gallon 1900/20=$95
Isabella spend= 100*10 + 90*15 =2350-->cost per gallon 2350/25=$94
Discount for Kim $5/gallon
Discount for Isabella $6/gallon
hence Isabella's total per-gallon discount is 120% (6/5*100) of Kim's total per-gallon discount.
consider cost per gallon as $100
Kim spend= 100*10 + 90*10 =1900-->cost per gallon 1900/20=$95
Isabella spend= 100*10 + 90*15 =2350-->cost per gallon 2350/25=$94
Discount for Kim $5/gallon
Discount for Isabella $6/gallon
hence Isabella's total per-gallon discount is 120% (6/5*100) of Kim's total per-gallon discount.
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Discount that Kim got=10%*10mitaliisrani wrote:During a special promotion, a certain filling station is offering a 10% discount on gas purchased after the first 10 gallons. If Kim purchased 20 gallons of gas and Isabella purchased 25 gallons of gas, then Isabella's total per-gallon discount is what percent of Kim's total per-gallon discount?
OA: D
Please help cant figure out how to go about the sum
per gallon discount=10%*10/20
Discount that Isabella got=10%*15
per gallon discount=10%*15/25
Ans=10%*15/25 / 10%*10/20=120% !
- harshavardhanc
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you just have to see on what quantity each will get discount. You need not bother about the actual discount %, since it will get canceled when you divide.mitaliisrani wrote:During a special promotion, a certain filling station is offering a 10% discount on gas purchased after the first 10 gallons. If Kim purchased 20 gallons of gas and Isabella purchased 25 gallons of gas, then Isabella's total per-gallon discount is what percent of Kim's total per-gallon discount?
OA: D
Please help cant figure out how to go about the sum
(15/25) / (10/20) * 100 = 120 %.
Regards,
Harsha
Harsha
- eaakbari
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Wow this is good, but could you elaborate as to how you came to this conclusion. I would have never thought of it. You rock Harshaharshavardhanc wrote:you just have to see on what quantity each will get discount. You need not bother about the actual discount %, since it will get canceled when you divide.mitaliisrani wrote:During a special promotion, a certain filling station is offering a 10% discount on gas purchased after the first 10 gallons. If Kim purchased 20 gallons of gas and Isabella purchased 25 gallons of gas, then Isabella's total per-gallon discount is what percent of Kim's total per-gallon discount?
OA: D
Please help cant figure out how to go about the sum
(15/25) / (10/20) * 100 = 120 %.
- harshavardhanc
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okies.eaakbari wrote:Wow this is good, but could you elaborate as to how you came to this conclusion. I would have never thought of it. You rock Harshaharshavardhanc wrote:you just have to see on what quantity each will get discount. You need not bother about the actual discount %, since it will get canceled when you divide.mitaliisrani wrote:During a special promotion, a certain filling station is offering a 10% discount on gas purchased after the first 10 gallons. If Kim purchased 20 gallons of gas and Isabella purchased 25 gallons of gas, then Isabella's total per-gallon discount is what percent of Kim's total per-gallon discount?
OA: D
Please help cant figure out how to go about the sum
(15/25) / (10/20) * 100 = 120 %.
Suppose Isa purchases T gallons and gets 10% discount on X. The discount amount/gallon will be : 10% * X / T.
Suppose kim purchases t gallons and gets 10% discount on Y. The discount amount/gallon will be : 10% * Y / t.
Hence, Isa's discount : Kim's discount is (10% * X / T) : (10% * Y / t) = (X/Y) * (t/T)
So that 10% doesn't matter. it will get canceled in the calculation.
Regards,
Harsha
Harsha