Question by Summer Clouds - Discuss with MathYouLike

Summer Clouds moderators

26/06/2017 at 09:05

A teacher has a list of marks: 17, 13, 5, 10, 14, 9, 12, 16. Which two marks can be removed without changing the averge?
A. 12 and 17
B. 5 and 17
C. 9 and 16
D. 10 and 12
E. 10 and 14

List of answers

Phan Thanh Tinh Coordinator 26/06/2017 at 11:17

The sum of the marks is : 17 + 13 + 5 + 10 + 14 + 9 + 12 + 16 = 96

The average of the marks is : 96 : 8 = 12

After removing 2 marks without changing the average,the sum of the marks is : 12 x (8 - 2) = 72

This sum decreased by : 96 - 72 = 24

In the given choices,there's only 10 + 14 = 24.Hence,the answer is E
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Trần Nhật Dương 26/06/2017 at 15:35

The sum of the marks is : 17 + 13 + 5 + 10 + 14 + 9 + 12 + 16 = 96

The average of the marks is : 96 : 8 = 12

After removing 2 marks without changing the average,the sum of the marks is : 12 x (8 - 2) = 72

This sum decreased by : 96 - 72 = 24

In the given choices,there's only 10 + 14 = 24.Hence,the answer is E

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