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datonman: Senior | Next Rank: 100 Posts; Posts: 53; Joined: Wed May 28, 2014 9:36 pmFollowed by: 1 member

by datonman » Sat Oct 31, 2015 4:56 pm

Three investors, A, B, and C, divide the profits from a business enterprise in the ratio of 5:7:8, respectively. If investor A earned $3,500, how much money did investors B and C earn in total?

A.)$4,000
B.)$4,900
C.)$5,600
D.)$9,500
E.)$10,500

From what I can understand is that the answer is given as 5+7+8=20. Investor A has 5 of these shares and Investors B and C are left with 20-5=15 profit shares. 15 is 3 times 5 and investors B and C earned three times that of Investor A. Thus, $3,500 X 3 = 10,500.

My problem is how did B and C receive 'three' times that of Investor A? (20-5=15?)

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Source: Beat The GMAT — Problem Solving | Sat Oct 31, 2015 4:56 pm

theCEO: Master | Next Rank: 500 Posts; Posts: 363; Joined: Sun Oct 17, 2010 3:24 pmFollowed by: 3 members; Thanked: 115 times

by theCEO » Sat Oct 31, 2015 5:29 pm

datonman wrote:Three investors, A, B, and C, divide the profits from a business enterprise in the ratio of 5:7:8, respectively. If investor A earned $3,500, how much money did investors B and C earn in total?

A.)$4,000
B.)$4,900
C.)$5,600
D.)$9,500
E.)$10,500

From what I can understand is that the answer is given as 5+7+8=20. Investor A has 5 of these shares and Investors B and C are left with 20-5=15 profit shares. 15 is 3 times 5 and investors B and C earned three times that of Investor A. Thus, $3,500 X 3 = 10,500.

My problem is how did B and C receive 'three' times that of Investor A? (20-5=15?)

A:B:C = 5:7:8

A shares = total shares x 5/(5+7+8)= total shares x 5/20
B+C shares = total shares x (7+8)/(5+7+8) = total shares x 15/20

B+C shares / A shares = (total shares x 15/20) / (total shares x 5/20)
B+C shares / A shares = (15/20) / (5/20) = (3/4) / (1/4) = 3/4 * 4/1 = 3

Therefore B+C received 3 times what A received = 3x3500 = 10500
ans = e

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

by [email protected] » Sun Nov 01, 2015 11:12 am

Hi datonman,

There are a variety of different ways to deal with ratio-based questions.

From the prompt, we know that Investor A received some 'multiple of 5' dollars. Once we're told that Investor A received $3500, we can figure out what that multiple is (3500/5 = 700). This means that Investor B received 7(700) = $4900 and Investor C received 8(700) = $5600.

B+C = $10,500 - this is 3 times $3500.

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

Contact Rich at [email protected]

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