1. According to Chebyshev's theorem, proportion of values from data set that is further than two standard deviations from mean is at most:

A. 0.50    

B. 0.13

C. 1.00

D. 0.25

2. In the study of elephants a researcher wishes to find out the average weight of the certain subspecies of elephants. From previous studies, the standard deviation of weights of elephants in this subspecies is known to be 1500 pounds. How many elephants does the researcher require to weigh so that he can be 80% confident that the average weight of elephants in his sample is in 350 pounds of true average weight for this subspecies?

A. 31       

B. 39       

C. 50       

D. 166     

3. A snack food manufacturer chosen a sample of 15 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 10.0 and sample standard deviation is 0.15, find out the 95% confidence interval estimate for true mean weight of bags of this kind of pretzel.

A. (9.92, 12.34)   

B. (8.54, 11.46)

C. (10.42, 10.58)

D. (9.92, 10.08)