Question

If n = 10

Mean X = 13

One value 20 was deleted

Find the new mean

Step by step. Why ??? and how???

please explaination.

Thank you~

Answer 1

The Mean is dividing the sum by the number of items.

The mean is another word for average.

The sample mean formula is: x̄ = ( Σ xi ) / n

• x̄ just a “sample mean”
• Σ means “summation”
• xi “all of the x-values”
• n means “the number of items in the sample”

As per your question If n = 10 Mean X = 13 then we can consider following set of numbers: 7 8 9 10 12 13 16 17 18 20

Then to find the mean for the following set of numbers: 7 8 9 10 12 13 16 17 18 20.we have to follow the following steps.

Step 1: Add up all of the numbers: 7+ 8+ 9 +10+ 12 +13+ 16 +17+ 18 +20=130

Step 2: Count the numbers of items in given set of numbers. there are 10 items.

Step 3: Divide the number you found in Step 1 by the number you found in Step 2. 130/10 = 13.

According to mean formula we will have mean X is:

x = ( Σ x_i ) / n
   = 130/10
x = 13

when the one value 20 was deleted in the following set of numbers: 7 8 9 10 12 13 16 17 18 20.Then we will have the following set of numbers: 7 8 9 10 12 13 16 17 18.

Then the new mean for set of numbers: 7 8 9 10 12 13 16 17 18 will be:

x = ( Σ x_i ) / n
   = 110/9
x = 12.22

Step 1: Add up all of the numbers: 7+ 8+ 9 +10+ 12 +13+ 16 +17+ 18 =110

Step 2: Count the numbers of items in given set of numbers. there are 9 items.

Step 3: Divide the number you found in Step 1 by the number you found in Step 2. 110/9 = 12.22.