BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

A team has to design a flag. The team has six blue strips...

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 2499
Joined: Sun Oct 29, 2017 2:04 pm
Followed by:6 members

A team has to design a flag. The team has six blue strips...

by swerve » Fri Jan 05, 2018 7:28 am
A team has to design a flag. The team has six blue strips of cloth and seven red strips of cloth that they must use as it to make the flag. How many different flags can the team design with the materials at hand?

A. 42
B. 120
C. 720
D. 1,716
E. 5,040

The OA is D.

Please, can any expert explain this PS question for me? I can't get the correct answer. I need your help. Thanks.
Top
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
Legendary Member
Posts: 503
Joined: Thu Jul 20, 2017 9:03 am
Thanked: 86 times
Followed by:15 members
GMAT Score:770

by ErikaPrepScholar » Fri Jan 05, 2018 7:59 am
Where we have a items of one type, b items of another type, c items of another, etc., we can solve for the number of permutations with the equation:
$$\frac{\left(a+b+c\ ...\right)!}{a!\cdot b!\cdot c!\ ...}$$
We have 13 total stripes. There are 6 of one kind (blue) and 7 of another kind (red). This gives us: $$\frac{(6+7)!}{6!7!}$$ $$\frac{13!}{6!7!}$$ $$\frac{13\cdot12\cdot11\cdot10\cdot9\cdot8}{6\cdot5\cdot4\cdot3\cdot2\cdot1}$$ $$\frac{13\cdot11\cdot9\cdot8}{6}$$ $$1716$$
Image

Erika John - Content Manager/Lead Instructor
https://gmat.prepscholar.com/gmat/s/

Get tutoring from me or another PrepScholar GMAT expert: https://gmat.prepscholar.com/gmat/s/tutoring/

Learn about our exclusive savings for BTG members (up to 25% off) and our 5 day free trial

Check out our PrepScholar GMAT YouTube channel, and read our expert guides on the PrepScholar GMAT blog
Top
Post new topic Post Reply
• Page 1 of 1