Question

A manufacturer of air conditioners claims that their air conditioners will draw 0.8 amp on average under normal conditions. A sample of 16 A/Cs was tested and the average current drawn was 0.98 amp with a standard deviation of 0.25 amp.

Would you use Z test or t test? (In your answer, Type only Z or t)

Answer 1

Solution :

Answer :  t

Explanation : We will use t - test. For example in hand we have to test for population mean. From the information given, we know that sample size is n= 16 (which is small). Sample mean Xbar=. 98 amp and sample standard deviation S = 0.25 amp. Population standard deviation is unknown.

For testing population mean with small sample size and unknown population standard deviation we use one sample t-test for testing population mean.

Hence we will use t-test.