Question by Lê Quốc Trần Anh - Discuss with MathYouLike

Lê Quốc Trần Anh Coordinator

15/08/2017 at 09:45

What number must be added to the set {5, 10, 15, 20, 25} to increase the mean by 5?

List of answers

Phan Thanh Tinh Coordinator 15/08/2017 at 10:28

The sum of 5 numbers in the set is : \(5+10+15+20+25=75\)

Their mean is : 75 : 5 = 15

After adding a number to the set,the mean of 6 numbers is :

15 + 5 = 20

Then, their sum is : 20 x 6 = 120

The number must be added is : 120 - 75 = 45
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phanhuytien 15/08/2017 at 15:27

The sum of 5 numbers in the set is : 5+10+15+20+25=755+10+15+20+25=75

Their mean is : 75 : 5 = 15

After adding a number to the set,the mean of 6 numbers is :

15 + 5 = 20

Their sum is : 20 x 6 = 120

The number must be added is : 120 - 75 = 45

Answer the 45

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