A medical laboratory tested 8 samples of human blood for acidity on the pH scale, with the results below. 7.1 7.5 7.6 7.4 7.3 7.3 7.3 7.5 a. Find the mean and standard deviation. b. What percentage of the data is within 2 standard deviations of the mean?

Mean = 7.38

SD = 0.148

b. 95%

Step-by-step explanation:

Given data is:

7.1 7.5 7.6 7.4 7.3 7.3 7.3 7.5

Mean:

Mean = Sum/No. of values

= (7.1+7.5+7.6+7.4+7.3+7.3+7.3+7.5) / 8

=59/8

=7.38

Standard Deviation:

x x-x' (x-x') ^2

7.1 - 0.28 0.0784

7.5 0.12 0.0144

7.6 0.22 0.0484

7.4 0.02 0.0004

7.3 - 0.08 0.0064

7.3 - 0.08 0.0064

7.3 - 0.08 0.0064

7.5 0.12 0.0144

Total : 0.1752

Variance = Sum of squares/No of items

= 0.1752/8 = 0.0219

SD = √0.0219 = 0.148

b. What percentage of the data is within 2 standard deviations of the mean?

95% of data is within two standard deviations of mean in a standard normal distribution ...