Target Test Prep 20% Off Flash Sale is on! Code: FLASH20

Redeem
Target Test Prep Flash Sale
Target Test Prep is 20% off right now!
Use code FLASH20

Available with Beat the GMAT members only code

MORE DETAILS
Magoosh
Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

MORE DETAILS
Magoosh

General Applied Problems - Coins

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Tue Jan 17, 2012 5:45 pm

General Applied Problems - Coins

by anastasios1984 » Tue Jul 03, 2012 7:10 am
I need help with the below.I am a bit confused...

Sue and Nancy wish to buy a snack. They combine their money and they have $4.00, consisting of quarters, dimes, and nickels. If they have 35 coins and the number of quarters is half the number of nickels, how many quarters do they have?

A - 3
B - 5
C - 6
D - 10
E - 20

Any ideas, i would like to see the approach to that kind of problems...

thanks in advance!
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Tue Jul 03, 2012 8:08 am
anastasios1984 wrote:I need help with the below.I am a bit confused...

Sue and Nancy wish to buy a snack. They combine their money and they have $4.00, consisting of quarters, dimes, and nickels. If they have 35 coins and the number of quarters is half the number of nickels, how many quarters do they have?

A - 3
B - 5
C - 6
D - 10
E - 20

Any ideas, i would like to see the approach to that kind of problems...

thanks in advance!
We can plug in the answers, which represent the number of quarters.
The number of nickels is double the number of quarters.
The remaining coins are dimes.

Answer choice C: 6 quarters, implying 12 nickels and 17 dimes
6(25) + 12(5) + 17(10) = 380 cents.
The sum must increase just a bit to 400 cents.
More quarters are needed.
Eliminate A, B, and C.
E more than triples the number of quarters; the result will be too great a sum.
Eliminate E.

The correct answer is D.
Last edited by GMATGuruNY on Tue Jul 03, 2012 1:01 pm, edited 1 time in total.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
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].
Student Review #1
Student Review #2
Student Review #3
Top
User avatar
Legendary Member
Posts: 520
Joined: Sat Apr 28, 2012 9:12 pm
Thanked: 339 times
Followed by:49 members
GMAT Score:770

by eagleeye » Tue Jul 03, 2012 10:58 am
anastasios1984 wrote:I need help with the below.I am a bit confused...

Sue and Nancy wish to buy a snack. They combine their money and they have $4.00, consisting of quarters, dimes, and nickels. If they have 35 coins and the number of quarters is half the number of nickels, how many quarters do they have?

A - 3
B - 5
C - 6
D - 10
E - 20

Any ideas, i would like to see the approach to that kind of problems...

thanks in advance!
Mitch gives a really good way of using "reasoning".

You could also do it using traditional algebra.
Let number of nickels(5 cents) be n, dimes(10 cents) be d and quarters(25 cents) be q.
We need to find q.

We are told that
1. n=2q (quarters are half the number of nickels)
2. n+d+q=35. (total number of coins is 35)
3. 5n+10d+25q=400 (Total sum is $4.00 or 400 cents).

Now we substitute for n and d in final equation to get the answer.
5n+10d+25q = 400
=> n+2d+5q=80
=> 2q+2*(35-q-2q)+5q=80 (substituting n=2q and d=35-q-n)
=> 7q-6q+70=80
=> q=10

Let me know if this helps :)
Top
Post new topic Post Reply
• Page 1 of 1