percentage off problem setup issue

Expert replies

GMatt08: Newbie | Next Rank: 10 Posts; Posts: 5; Joined: Wed Mar 05, 2008 9:59 am; Location: Arlington, VA

by GMatt08 » Mon Mar 10, 2008 9:46 am

Kind of confused on how to set this one up:

An instrument store gives a 10% discount to all students off the original cost of an instrument. During a back to school sale an additional 15% is taken off the discounted price. Julie, a student at the local high school, purchases a flute for $306. How much did it originally cost?

A $325
B $375
C $400
D $408
E $425

Thanks for any help y'all can give!

-Matt

Like this post

Source: Beat The GMAT — Problem Solving | Mon Mar 10, 2008 9:46 am

tmmyc: Senior | Next Rank: 100 Posts; Posts: 72; Joined: Mon Mar 10, 2008 10:29 am; Thanked: 25 times

by tmmyc » Mon Mar 10, 2008 10:43 am

This is how I would set up this question.

Set 'x' as the original cost of the instrument.

Julie first gets a 10% discount. This means she only pays 90% of the original cost.

x*.9

Then, Julie gets an additional 15% off the discounted price. She only pays 85% of the discounted price.

(x*.9)*.85

Julie pays $306, so

(x*.9)*.85 = 306

Solve for x.

Last edited by tmmyc on Mon Mar 10, 2008 12:52 pm, edited 1 time in total.

Like this post

smar83: Senior | Next Rank: 100 Posts; Posts: 91; Joined: Mon Dec 31, 2007 4:54 pm; Location: Houston; Thanked: 1 times

by smar83 » Mon Mar 10, 2008 10:45 am

That's correct. 400 is the answer.

Like this post

GMatt08: Newbie | Next Rank: 10 Posts; Posts: 5; Joined: Wed Mar 05, 2008 9:59 am; Location: Arlington, VA

by GMatt08 » Mon Mar 10, 2008 11:18 am

Oh that makes so much sense now! Thank you!

I'm so rusty on math but it's starting to come back slowly.

Very appreciated,

-Matt

Like this post

ikant: Senior | Next Rank: 100 Posts; Posts: 62; Joined: Wed Mar 05, 2008 8:57 am; Location: mumbai, India; Thanked: 5 times

by ikant » Mon Mar 10, 2008 7:44 pm

Hello all,

Since you have sen the theory behind sucessive discount problems, I may give you a formula that is very handy to crack these problems.

When two successive discounts are given of a% and b% then the net discount offered = a + b - (a*b)/100

Once you get the net discount percentage, one can easily claculate the price.

Cheers,
iKant

"To do is to be"

Like this post

gmat765: Senior | Next Rank: 100 Posts; Posts: 58; Joined: Wed Apr 16, 2008 5:51 pm

by gmat765 » Thu Apr 17, 2008 7:40 pm

I will go with c, too

Like this post

AleksandrM: Legendary Member; Posts: 566; Joined: Fri Jan 04, 2008 11:01 am; Location: Philadelphia; Thanked: 31 times; GMAT Score:640

by AleksandrM » Fri Apr 18, 2008 9:26 am

You could also just backsolve. Pick 375 and multiply it by 10%, you get a result with change, which means that there will be change in the answer, which means that it is wrong. Pick 408, same result. Try 400:

400(.10) = 40

400 - 40 = 360

360(.15) = 54

360 - 54 = 306

This all took me under 2 minutes.

https://second-lap.blocked/

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review