Question

Write the null and alternative hypotheses for each of the following examples. Determine if each is a case of a two-tailed, a left-tailed, or a right-tailed test. (a) To test if the mean number of hours spent working per week by college students who hold jobs is different from 20 hours (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 length of experience of airport security guards is different from 3 years (d) To test if the mean credit card debt of college seniors is less than $1000 (e) 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

Answer 1

(a) To test if the mean number of hours spent working per week by college students who hold jobs is different from 20 hours
Two tailed

Below are the null and alternative Hypothesis,
Null Hypothesis: μ = 20
Alternative Hypothesis: μ ≠ 20

(b) To test whether or not a bank’s ATM is out of service for an average of more than 10 hours per month
Right tailed

Below are the null and alternative Hypothesis,
Null Hypothesis: μ = 10
Alternative Hypothesis: μ > 10

(c) To test if the mean length of experience of airport security guards is different from 3 years
Two tailed

Below are the null and alternative Hypothesis,
Null Hypothesis: μ = 3
Alternative Hypothesis: μ ≠ 3

(d) To test if the mean credit card debt of college seniors is less than $1000
Left tailed

Below are the null and alternative Hypothesis,
Null Hypothesis: μ = 1000
Alternative Hypothesis: μ < 1000

(e) 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
Right tailed

Below are the null and alternative Hypothesis,
Null Hypothesis: μ = 12
Alternative Hypothesis: μ > 12