A public bus company official claims that the mean waiting time ...

[mcmcdaniel]

A public bus company official claims that the mean waiting time for bus number 14 during peak hours is less than 10 minutes.
 
  Karen took bus number 14 during peak hours on 18 different occasions. Her mean waiting time was 7.5 minutes with a standard deviation of 2.1 minutes. At the 0.01 significance level, test the claim that the mean is less than 10 minutes.

Question 2

A researcher wants to check the claim that convicted burglars spend an average of 18.7 months in jail.
 
  She takes a random sample of 11 such cases from court files and finds that = 20.6 months and s = 7.1 months. Test the null hypothesis that  = 18.7 at the 0.05 significance level.

[mbcrismon]

Answer to Question 1

Test statistic: t = -5.05. Critical values: t = -2.567. Reject . There is sufficient evidence to support the claim that the mean is less than 10 minutes.

Answer to Question 2

Test statistic: t = 0.89. Critical values: t = 2.228. Fail to reject . There is not sufficient evidence to warrant rejection of the claim that the mean is 18.7 months.

[mcmcdaniel]

Excellent

[aliotak]

Gracias!