Question 14

The mean of a set of 12 numbers is 24. If one item is excluded, the mean gets reduced by 3. What is the excluded number?

Solution

mean of a set of 12 numbers is 24.

total of 12 numbers = $$ 12 \times 24 = 288 $$

one item is excluded the total numbers becomes 11 and  the mean gets reduced by 3

let the excluded number be x and the new mean = 21

according to the question

$$ \frac{288 - x}{11} = 21 $$

solving x = 57

excluded number = 57


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