Question

the mean of 100 observations is 45. if it later found that two observations 19 and 31 were incorrectly recorded 91 and 13 the correct mean

Answer 1

We know that the mean is found by taking the sum of the numbers and dividing it by the amount of numbers that were within the sum, so we can reverse this and find that the sum of the 100 observations was 4500

From here, we can subtract the 91 and the 13 that were incorrect.

so $4500-91-13=4396$

Next we can add the correct values

$4396+19+31=4446$

As there are still 100 observations, we now need to divide the sum by 100.

$\frac{4446}{100} = 44.46$

So the mean is now 44.46

Answer 2

Answer:

Mean = 45

100

x

=45⇒x=4500

Two number (91+13)=104 incorrect

So let sum = 4500 – 104 = 4396

Add correct number 19+31 = 50

= 4396+50 = 4446

Mean =

100

4446

=44.46

Step-by-step explanation:

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