Lisa gave four English tests last week. The score of her fourth test was 8 more than the average score of her first thre

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Gmat_mission: Legendary Member; Posts: 1622; Joined: Thu Mar 01, 2018 7:22 am; Followed by:2 members

Lisa gave four English tests last week. The score of her fourth test was 8 more than the average score of her first thre

by Gmat_mission » Sun Dec 27, 2020 3:43 pm

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Lisa gave four English tests last week. The score of her fourth test was 8 more than the average score of her first three tests. How much greater is her fourth test score than the average score of four tests?

A. 2
B. 4
C. 6
D. 8
E. 10

Answer: C

Source: e-GMAT

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Source: Beat The GMAT — Problem Solving | Sun Dec 27, 2020 3:43 pm

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

Re: Lisa gave four English tests last week. The score of her fourth test was 8 more than the average score of her first

by Scott@TargetTestPrep » Mon Mar 22, 2021 8:29 am

Gmat_mission wrote: ↑
Sun Dec 27, 2020 3:43 pm
Lisa gave four English tests last week. The score of her fourth test was 8 more than the average score of her first three tests. How much greater is her fourth test score than the average score of four tests?

A. 2
B. 4
C. 6
D. 8
E. 10

Answer: C

Solution:

We can let x = the average of the first 3 tests. Thus, her fourth test, in terms of x, is x + 8, and the average of all 4 tests is:

(3x + x + 8) / 4 = (4x + 8) / 4 = x + 2

Therefore, her fourth test is (x + 8) - (x + 2) = 6 points higher than the average of all 4 tests.

Answer: C

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