Write the null and alternative hypotheses for the following example. Determine if the example is a case of a two-tailed, a left-
tailed, or a right-tailed test. (a) To test if the mean time a customer has to wait on the phone to speak to a representative of a mailorder company about unsatisfactory service is more than 12 minutes.
(b) To test whether or not a bank's ATM is out of service for an average of more than 10 hours per month
(c) To test if the mean credit card debt of college seniors is less than $100
(d) To test if the mean time a customer has to wait on the phone to speak to a representative of a mail-order company about unsatisfactory service is more than 12 minutes
This is a right tailed test ; the alternative hypothesis has a greater than sign, difference between sample and population mean value will be positive.
(b)
H0 : μ = 10
H1 : μ > 10
This is a right tailed test ; the alternative hypothesis has a greater than sign, difference between sample and population mean value will be positive.
(c)
H0 : μ = 100
H1 : μ < 100
This is a left tailed test ; the alternative hypothesis has a less than sign, difference between sample and population mean value will be negative.
(d)
H0 : μ = 12
H1 : μ > 12
This is a right tailed test ; the alternative hypothesis has a greater than sign, difference between sample and population mean value will be positive.
