The _____ denotes the number of standard deviations xi is from the mean .
a. variance
b. median
c. z-score
d. normal deviation
Question 2
In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately
a. .39.
b. 1.96.
c. .20.
d. 1.64.