PS Mixtures

This topic has expert replies
Junior | Next Rank: 30 Posts
Posts: 11
Joined: Sun Jul 08, 2012 11:27 pm
Thanked: 1 times

PS Mixtures

by sreenunna » Wed Nov 14, 2012 4:50 am
According to the directions on a can of frozen orange juice concentrate, 1 can of concentrate is to be mixed with 3 cans of water to make orange juice. How many 12-ounce cans of the concentrate are required to prepate 200 6-ounce servings of orange juice?

A) 25
B) 34
C) 50
D) 67
E) 100

Official Answer is revealed later and the question is from GMAT official source
Source: — Problem Solving |

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 » Wed Nov 14, 2012 5:14 am
sreenunna wrote:According to the directions on a can of frozen orange juice concentrate, 1 can of concentrate is to be mixed with 3 cans of water to make orange juice. How many 12-ounce cans of the concentrate are required to prepate 200 6-ounce servings of orange juice?

A) 25
B) 34
C) 50
D) 67
E) 100

Official Answer is revealed later and the question is from GMAT official source
Total = 200 6-ounce servings = 200*6 = 1200 ounces.
Since each can = 12 ounces, the total = 1200/12 = 100 cans.
In these 100 cans of mixture, since concentrate:water = 1:3 and 1+3=4, concentrate/total = 1/4.
Thus, in the 100 cans of mixture, the number of cans of concentrate = (1/4)100 = 25.

The correct answer is A.
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

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Wed Nov 14, 2012 7:23 am
sreenunna wrote:According to the directions on a can of frozen orange juice concentrate, 1 can of concentrate is to be mixed with 3 cans of water to make orange juice. How many 12-ounce cans of the concentrate are required to prepate 200 6-ounce servings of orange juice?

A) 25
B) 34
C) 50
D) 67
E) 100
Here's a slightly different approach that uses equivalent ratios.

The first part tells that, for every 1 can of concentrate, we can make 4 cans of juice.
Let's be even more generic, for 1 volume of concentrate, we can make 4 volumes of juice.

Okay, now notice that we have a problem with the volume mismatch in the question. It involves 12-ounce cans of concentrate and 6-ounce servings.
So, let's reword the question. Instead of making 200 6-ounce servings of juice, let's make 100 12-ounce servings of juice. This is acceptable since we're still making the same amount of juice!

We're now asking, "How many 12-ounce cans of the concentrate are required to prepare 100 12-ounce serving of orange juice?

We'll solve this question using equivalent ratios.

(volume of concentrate)/(volume of juice): 1/4 = x/100

Solve for x to get [spoiler]x=25[/spoiler]
So, the answer is A

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image