Consider the data set 4, 4, 4, 4, 4, 4, 4, 4.

a. Guess the value of the sample standard deviation without calculating it. Explain your reasoning.

b. Use the defining formula to calculate the sample standard deviation.

c. Complete the following statement and explain your reasoning: If all observations in a data set are equal, the sample standard deviation is .

d. Complete the following statement and explain your reasoning: If the sample standard deviation of a data set is 0, then . . . .