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# Due to a sudden 20% increase in price, one is now able to buy 4 gallon

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Manager
Joined: 07 Jun 2017
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Due to a sudden 20% increase in price, one is now able to buy 4 gallon  [#permalink]

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17 Oct 2017, 05:28
6
00:00

Difficulty:

75% (hard)

Question Stats:

57% (02:36) correct 43% (02:44) wrong based on 94 sessions

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Due to a sudden 20% increase in price, one is now able to buy 4 gallons lesser oil than earlier on the same expenditure of
$600. What is the dollar increase in the price of oil per gallon? A.$2
B. $5 C.$10
D. $20 E.$25

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email: nkmungila@gmail.com
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Due to a sudden 20% increase in price, one is now able to buy 4 gallon  [#permalink]

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17 Oct 2017, 06:14
nkmungila wrote:
Due to a sudden 20% increase in price, one is now able to buy 4 gallons lesser oil than earlier on the same expenditure of
$600. What is the dollar increase in the price of oil per gallon? A.$2
B. $5 C.$10
D. $20 E.$25

Test the answers. The equation for this one was taking too long. Backsolving was quick.

(Price per gallon P) * (# of gallons Q) = Total cost

Q = Total cost/price per gallon

1) Find original price from given dollar increase

2) Find original # of gallons by dividing $600 by old price per gallon 3) Find new price = (1.2)($old), OR
($Old price + added$ increase)

4) Find new # gallons. Divide 600 by new price

Answer C) $10$10 is both the dollar increase in price and a .20 increase of original price, x

Original price:

$10 = .2x = $$\frac{10}{.2} = 50$$ Original number of gallons: $$\frac{600}{50PerGal} = 12$$ gallons New price:$50 + $10 (or 1.2 *$50) = $60 New number of gallons $$\frac{600}{60per} = 10$$ gallons 12 - 10 = 2 fewer gallons now. Too small. That means the dollar price increase is too large. To increase quantity, decrease price. Try B)$5

$5 = .2x Original price: $$\frac{5}{.2} = 25$$ Original quantity: $$\frac{600}{25per} = 24$$ gallons New price: (1.2)($25) or ($25 +$5) = $30 New quantity: $$\frac{600}{30per} = 20$$ gallons 24 - 20 = 4 gallons. Correct Answer B _________________ SC Butler has resumed! Get two SC questions to practice, whose links you can find by date, here. Instructions for living a life. Pay attention. Be astonished. Tell about it. -- Mary Oliver Target Test Prep Representative Status: Founder & CEO Affiliations: Target Test Prep Joined: 14 Oct 2015 Posts: 8117 Location: United States (CA) Re: Due to a sudden 20% increase in price, one is now able to buy 4 gallon [#permalink] ### Show Tags 19 Oct 2017, 10:16 nkmungila wrote: Due to a sudden 20% increase in price, one is now able to buy 4 gallons lesser oil than earlier on the same expenditure of$600. What is the dollar increase in the price of oil per gallon?

A. $2 B.$5
C. $10 D.$20
E. $25 We can let the original number of gallons of oil = n and the original price = p; thus: np = 600 and (1.2p)(n - 4) = 600 1.2np - 4.8p = 600 Substituting 600 for np in the above equation, we have: 1.2(600) - 4.8p = 600 720 - 4.8p = 600 120 = 4.8p 25 = p The old price was 25, and the new price is 20% more: 25 x 1.2 = 30. Thus, the increase in price is 5 dollars. Answer: B _________________ # Scott Woodbury-Stewart Founder and CEO Scott@TargetTestPrep.com 122 Reviews 5-star rated online GMAT quant self study course See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews If you find one of my posts helpful, please take a moment to click on the "Kudos" button. Intern Joined: 16 Jan 2017 Posts: 10 Re: Due to a sudden 20% increase in price, one is now able to buy 4 gallon [#permalink] ### Show Tags 20 Oct 2018, 12:35 Can we solve this using a logical approach?? Manager Joined: 14 Jun 2018 Posts: 217 Re: Due to a sudden 20% increase in price, one is now able to buy 4 gallon [#permalink] ### Show Tags 20 Oct 2018, 12:51 3 Let the price of gasoline be x. New Price = 1.2x $$\frac{600}{x} - \frac{600}{1.2x} = 4$$ 120 = 4.8x x = 25 New price = 30 Increase = 5$
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Re: Due to a sudden 20% increase in price, one is now able to buy 4 gallon  [#permalink]

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20 Oct 2018, 13:12
1
castiel wrote:
Can we solve this using a logical approach??

Apart from algebra you could solve it using percentage.

Initial amount = 100
Now price increased by 20% = 120
Since the price increased , you need to decrease consumption by 20/120 * 100 = 16.67% or 1/6 to keep your expenditure the same.

This 16.67% decrease = 4 units of gasoline
Therefore , 100% = 24 units of gasoline
Initial quality = 24 units ; Initial price = 600/24 = 25$Final quantity = 20 units ; Final Price = 600/20 = 30$

Increase = 5\$
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Due to a sudden 20% increase in price, one is now able to buy 4 gallon  [#permalink]

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21 Oct 2018, 01:34
Got it!

Thanks pandeyashwin
Due to a sudden 20% increase in price, one is now able to buy 4 gallon   [#permalink] 21 Oct 2018, 01:34
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