Question

The pH of a solution is measured eight times by one operator using the same instrument. She obtains the following data: 7.15, 7.20, 7.18, 7.19, 7.21, 7.20, 7.16, and 7.20. (a) Calculate the sample mean. Round your answer to 3 decimal places.

Answer 1

7.186

Step-by-step explanation:

The mean is the average of some given data from a sample point.

To calculate the mean, we use the formula below:

Mean = ∑fx/∑f

Where f = frequency

x = sample data

From the given pH of the solutions, we can form a table:

x f fx

7.15 1 7.15

7.16 1 7.16

7.18 1 7.18

7.19 1 7.19

7.20 3 21.6

7.21 1 7.21

Now ∑fx = 7.15 +7.16 +7.18 + 7.19 + 7.20 + 7.21 = 57.49

∑f = 1 + 1 + 1 + 1 + 3 + 1 = 8

The mean =
`(57.49)/(8)` = 7.18625 = 7.186