A large box contains 10,000 ball bearings. A random sample of 120 is chosen. The sample mean diameter is 10 mm, and the standard deviation is 0.24 mm. True or false:

a. A 95% confidence interval for the mean diameter of the 120 bearings in the sample is 10 ±
(1.96)(0.24)∕
√
120.

b. A 95% confidence interval for the mean diameter of the 10,000 bearings in the box is 10 ±
(1.96)(0.24)∕
√
120.

c. A 95% confidence interval for the mean diameter of the 10,000 bearings in the box is 10 ±
(1.96)(0.24)∕
√10,000.