Question

The mean of 5 observations is 7.Later on it was found that two observations 4 and 8 were wrongly taken instead of 5 and 9.Find the correct mean

Answer 1

Hey there !

Mean = 7

Number of observations = 5

=> Sum of observations = 7 * 5 = 35

But two observations were taken wrong.

Sum of wrong observations = 4 + 8 = 12

Sum of correct observations = 5 + 9 = 14

So New sum = 35 - 12 + 14

=> New Sum = 37

So new mean = 37 / 5 = 7.4

Hope my answer helped !

Answer 2

$\textbf {Hey there, here is the solution.}$

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STEP 1: Find the total of the 5 observations:

Mean of the 5 observations = 7

Sum of the 5 observations = 5 x 7 = 35

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STEP 2: Take away the 2 observations that are wrong:

Sum of the 3 right observations = 35 - 4 - 8 = 23

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STEP 3: Add back the 2 observations that are correct:

Sum of the 5 observations = 23 + 5 + 9 = 37

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Find the mean of the 5 observations:

37 ÷ 5 = 7.4

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Answer: The correct mean is 7.4

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⭐$\textbf {Cheers @ Simmisai}$⭐