This question is incomplete, in that the Excel File: data07-11.xlsx a. was not provided, but I was able to get the information on the Excel File: data07-11.xlsx a. from google as below:
57 61 86 74 72 73
20 57 80 79 83 74
The image of the Excel File: data07-11.xlsx a. is also attached below.
Answer:
a) Point estimate of sample mean = 68
b) Point estimate of standard deviation (4 decimals) = 17.8122
Explanation:
a) Point estimate of sample mean, \bar{x} = ∑Xi / n = (57 + 61 + 85 + 74 + 73 + 72 + 20 + 58 + 81 + 78 + 84 + 73)/12 = 68
b) Point estimate of standard deviation = sqrt ∑ Xi² - n\bar{x}² / n-1)
= sqrt(((57 - 68)^2 + (61 - 68)^2 + (85 - 68)^2 + (74 - 68)^2 + (73 - 68)^2 + (72 - 68)^2 + (20 - 68)^2 + (58 - 68)^2 + (81 - 68)^2 + (78 - 68)^2 + (84 - 68)^2 + (73 - 68)^2)/11) = 17.8122