Fox jeans regularly sell for $15 a pair and Pony jeans regularly sell for $18 a pair. During a sale these regular unit prices are discounted at different rates so that a total of $9 is saved by purchasing 5 pairs of jeans: 3 pairs of Fox jeans and 2 pairs of Pony jeans. If the sum of the two discounts rates is 22 percent, what is the discount rate on Pony jeans?
(A) 9%
(B) 10%
(C) 11%
(D) 12%
(E) 15%
The answer is 10%. How is the answer arrived at?
Observations:
- Seems Time Consuming GMAT Practice Question
- Seems "calculation intensive" GMAT Practice Question
Methods:
- First step of any gmat problem solving question must be to formulate equations
- There are two methods (1) Solve the equations and get the answer to gmat practice question (2) Use logic and backsolving techniques (if you can)
First write the equations:
3*(15 - 15x/100) + 2*(18-18y/100) = 3*15 + 18*2 - 9
==> -45x/100 -36y/100 = -9
x/100 + y/100 = 22/100
Now you can solve the equtions .. but I would recommend, just using back solving
The answer choices gives "y" , so u can calculate "x" from (ii)
A) y=9 => x=13
13, 9
(i) can be written as -45*13 - 36*9 = -900
instead of multiplying, just look at the units digits of the two terms: 4, 8 .. can the sum have "0" as units digit => NO .. so this is out
Similatly
B) 12 , 10
units digits .. 0, 0 .. possible
C) 11, 11
units digit 5, 6 ..no
D) 10 , 12
0, 2 ... no
E) 7, 15
5, 0 .. no
So only B is possible ... hence (B) should be the answer.
remember .. in GMAT its not "how" you get the correct answer its about getting the correct answer ( thought process counts for NADA )
~|Guardian|
I am an instructor on ScoreChase GMAT Crash Course . I also provide GMAT Private Tutoring sessions.
I find it much easier directly going to answer choices. Trying 9% & 13%, 10% & 12%, ...... on the regular selling amount (15*3=45 and 18*2=36) which gives a total discount figure of $9 is easier I think. ans. D
Last edited by Jilany; December 8th, 2009 at 08:51 PM.
Nurul Hai
I guess this approach gives you quick answer
Let x be the discount rate on Fox jeans and y - on Pony jeans, then the equation is
15*3*x+2*8*y=9,
and x+y=0.22. From here it can be found that x=1.08/9=0.12. So the answer is D
For me solving with equations is more simple. Though this appears to be very time consuming during the test
eqn solving may be simple for me too
The answer is B- 10%
here is how you go about it, use the options given to you, lets assume the Pony jeans discount is 10% which means discount is $1.8 per pair and $3.6 for 2 pairs
this means the discount on fox jeans is 12% which means $1.8 per pair and $5.4 for 3 pairs, total discount is $9.00 (5.4 + 3.6), and total discount percent is 22 (12+10).
How did anyone get D as the correct answer?
Yeap, i hurried up. It's 10%. I indicated the discount of Fox jeans, not Pony. Thanks for mentioning
Sorry 12% discount is for Fox jeans not for Pony jeans.
Answer is B
Nurul Hai
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