An analyst will recommend a combination of

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

Redeem

This topic has expert replies

Post new topic Post Reply

Previous Topic Next Topic

NandishSS: Master | Next Rank: 500 Posts; Posts: 366; Joined: Fri Jun 05, 2015 3:35 am; Thanked: 3 times; Followed by:2 members

An analyst will recommend a combination of

by NandishSS » Sun Dec 18, 2016 6:10 am

An analyst will recommend a combination of 3 industrial stocks, 2 transportation stocks, and 2 utility stocks. If the analyst can choose from 5 industrial stocks, 4 transportation stocks, and 3 utility stocks, how many different combinations of 7 stocks are possible?

A. 12
B. 19
C. 60
D. 180
E. 720

OA:D

Source-GMATPrep EP2

Quote

Source: Beat The GMAT — Problem Solving | Sun Dec 18, 2016 6:10 am

GMATGuruNY: 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 » Sun Dec 18, 2016 6:26 am

NandishSS wrote:An analyst will recommend a combination of 3 industrial stocks, 2 transportation stocks, and 2 utility stocks. If the analyst can choose from 5 industrial stocks, 4 transportation stocks, and 3 utility stocks, how many different combinations of 7 stocks are possible?

A. 12
B. 19
C. 60
D. 180
E. 720

From 5 industrial stocks, the number of ways to choose 3 = 5C3 = (5*4*3)/(3*2*1) = 10.
From 4 transportation stocks, the number of ways to choose 2 = 4C2 = (4*3)/(2*1) = 6.
From 3 utility stocks, the number of ways to choose 2 = 3C2 = (3*2)/(2*1) = 3.
To combine these options, we multiply:
10*6*3 = 180.

The correct answer is D.

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

Quote

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pm; Location: Palo Alto, CA; Thanked: 2867 times; Followed by:511 members; GMAT Score:800

by [email protected] » Sun Dec 18, 2016 10:56 am

Hi NandishSS,

In these types of multi-combination questions, you normally just have to find the individual number of combinations for each element, then multiply the results together.

From the information provided, the number of combinations of...

Industrial stocks = 5C3 = 10 possible combinations
Transportation stocks = 4C2 = 6 possible combinations
Utility stocks = 3C2 = 3 possible combinations

(10)(6)(3) = 180 possible combinations of 7 stocks.

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

Quote

GMAT/MBA Expert

Jay@ManhattanReview: GMAT Instructor; Posts: 3008; Joined: Mon Aug 22, 2016 6:19 am; Location: Grand Central / New York; Thanked: 470 times; Followed by:34 members

by Jay@ManhattanReview » Mon Dec 19, 2016 2:01 am

NandishSS wrote:An analyst will recommend a combination of 3 industrial stocks, 2 transportation stocks, and 2 utility stocks. If the analyst can choose from 5 industrial stocks, 4 transportation stocks, and 3 utility stocks, how many different combinations of 7 stocks are possible?

A. 12
B. 19
C. 60
D. 180
E. 720

OA:D

Source-GMATPrep EP2

From the given 5 industrial stocks, the number of ways to choose 3 industrial stocks = 5C3 = 5C2 = (5*4)/(2*1) = 10.

We know that nCr = nC(n-r); if r > n/2, you must use this equivalent to ease the caculation. Remeber that nPr not equal to nP(n-r)

From 4 transportation stocks, the number of ways to choose 2 transportation stocks = 4C2 = 4C2 = (4*3)/(2*1) = 6.

From 3 utility stocks, the number of ways to choose 2 utility stocks = 3C2 = 3C1 = 3.

Number of different combinations of 7 stocks = 10*6*3 = 180.

OA: D.

-Jay

_________________
Manhattan Review GMAT Prep

Locations: New York | Jakarta | Nanjing | Berlin | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.

Quote

GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8083; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Wed Dec 21, 2016 8:55 am

NandishSS wrote:An analyst will recommend a combination of 3 industrial stocks, 2 transportation stocks, and 2 utility stocks. If the analyst can choose from 5 industrial stocks, 4 transportation stocks, and 3 utility stocks, how many different combinations of 7 stocks are possible?

A. 12
B. 19
C. 60
D. 180
E. 720

OA:D

We have a basic combination problem in which an analyst has to select 3 industrial stocks from 5, 2 transportation stocks from 4, and 2 utility stocks from 3. Let's determine the number of ways to select each type of stock.

3 industrial stocks from 5: 5C3 = (5 x 4 x 3)/3! = (5 x 4 x 3)/(3 x 2 x 1) = 10 ways

2 transportation stocks from 4: 4C2 = (4 x 3)/2! = (4 x 3)/(2 x 1) = 6 ways

2 utility stocks from 3: 3C2 = (3 x 2)/2! = (3 x 2)/(2 x 1) = 3 ways

Since the analyst is choosing all 3 types of stocks, there are 10 x 6 x 3 = 180 ways to select the stocks.

Answer: D

Scott Woodbury-Stewart
Founder and CEO
[email protected]