What is the FASTEST method to solve the question given below.
A man spends 70% of his salary on food expenses, 40% of the rest on traveling expenses, 90% of the rest on house rent and was finally left with $3600. How much did he spend on traveling expenses?
A. 24000
B. 18000
C. 25000
D. 22000
E. 20000
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GMATGuruNY
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To determine the ratio, let the salary = 1000.eaakbari wrote:What is the FASTEST method to solve the question given below.
A man spends 70% of his salary on food expenses, 40% of the rest on traveling expenses, 90% of the rest on house rent and was finally left with $3600. How much did he spend on traveling expenses?
A. 24000
B. 18000
C. 25000
D. 22000
E. 20000
Food = .7(1000) = 700.
Remainder = 1000-700 = 300.
Travel = .4(300) = 120.
Remainder = 300-120 = 180.
Since 90% of the remainder is spent on rent, the amount left after rent = .1(180) = 18.
Travel : amount left = 120:18.
Since the ACTUAL amount left = 3600, and 3600/18 = 200, the multiplier for the ratio is 200:
Travel : amount left = 200(120:18) = 24000:3600.
Thus, travel = 24000.
The correct answer is A.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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Another approach is to work backwards.eaakbari wrote: A man spends 70% of his salary on food expenses, 40% of the rest on traveling expenses, 90% of the rest on house rent and was finally left with $3600. How much did he spend on traveling expenses?
A. 24000
B. 18000
C. 25000
D. 22000
E. 20000
At the end, the man spent 90% of some amount on house rent and was finally left with $3600.
So, if X = the $ he had before paying the rent, we know that:
- 90% of X = rent
- The remaining 10% of X = 3600 (in other words, 0.1X = 3600)
This tells us that X = 36,000
In other words, he had $36,000 BEFORE paying the rent.
Now move back a step.
The man spent 40% of some amount on travel and was left with $36,000.
So, if Y = the $ he had before paying for travel, we know that:
- 40% of Y = travel
- The remaining 60% of Y = 36,000 (in other words, 0.6Y = 36,000)
We can solve this equation to see that Y = 60,000
So Y = 60,000 and 40% of this was spent on travel.
40% of 60,000 = 24,000 so the answer is A
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
