Oil A and Oil B.

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

vk_vinayak: Legendary Member; Posts: 502; Joined: Tue Jun 03, 2008 11:36 pm; Thanked: 99 times; Followed by:21 members

Oil A and Oil B.

by vk_vinayak » Mon Aug 27, 2012 2:53 am

A certain industrial machine requires 15 quarts (480 ounces) of oil every day, and it is given a mixture of oil A and oil B. Oil A consists of 5% special additives while oil B consists of 8% special additives. If the machine needs exactly 30 ounces of the special additives to ensure smooth operation, then how much of oil A, in ounces, should be in the mixture?

A. 260
B. 280
C. 290
D. 300
E. 320

- VK

I will (Learn. Recognize. Apply)

Quote

Source: Beat The GMAT — Problem Solving | Mon Aug 27, 2012 2:53 am

GaneshMalkar: Senior | Next Rank: 100 Posts; Posts: 77; Joined: Tue Jul 31, 2012 6:53 am; Thanked: 8 times; Followed by:1 members

by GaneshMalkar » Mon Aug 27, 2012 3:30 am

vk_vinayak wrote:A certain industrial machine requires 15 quarts (480 ounces) of oil every day, and it is given a mixture of oil A and oil B. Oil A consists of 5% special additives while oil B consists of 8% special additives. If the machine needs exactly 30 ounces of the special additives to ensure smooth operation, then how much of oil A, in ounces, should be in the mixture?

A. 260
B. 280
C. 290
D. 300
E. 320

A question of just trial and error as the values are far apart....

Start with value C which is 290

290 - 5% = 14.5
190(480 - 290) - 8% - 15.2
total = 29.7 which is less than 30 by 0.3

so we need to go less for Oil A

280 - 5% = 14
200 - 8% = 16
total = 30

So the correct answer is 280 for Oil A:)

If you cant explain it simply you dont understand it well enough!!!
- Genius

Quote

das.ashmita: Master | Next Rank: 500 Posts; Posts: 118; Joined: Mon May 21, 2012 10:07 pm; Thanked: 23 times; Followed by:4 members

by das.ashmita » Tue Aug 28, 2012 1:53 am

A simpler approach

let the amount of A in mixture be x and amount of B be (480-x)
0.05x + 0.08(480-x) = 30
=>x = 280

Hence Ans B

Quote

everything's eventual: Master | Next Rank: 500 Posts; Posts: 101; Joined: Sun Jun 03, 2012 10:10 pm; Thanked: 10 times; Followed by:1 members