Question

mean of 5 numbers is 7. if one number is excluded the mean gets reduced by 2. determine the excluded number
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Answer 1

Given mean of 5 numbers = 7
Sum of the observations = 5 × 7 = 35
Let the no excluded be y
Now no.of observations = 4
Sum of observations = 35 - y
Given that now the mean is reduced by 2 = 7-2 = 5
⇒ (35-y)/4 = 5
⇒ 35-y = 5×4
⇒ 35-y = 20
⇒ -y = 20-35
⇒ -y = -15
⇒ y = 15
∴ The excluded no is 15