A rechargeable flashlight is advertised to last up to 2 1/2 hours ...

[Frost2351]

A rechargeable flashlight is advertised to last up to 2 1/2 hours per charge and to recharge overnight. A test was conducted which measured the time a light lasted before needing a recharge. A random sample of 12 lights has a mean recharge time of 2.24 hours and a standard deviation of 1.05 hours. Assuming the population for recharge time is normally distributed, what is the 99 confidence interval estimate for the population mean? ___________________ _ to ___________________ _
 Fill in the blank(s) with correct word

Question 2

An economics professor is taping 60-minute lectures for replay over the university radio station. To make sure that the brand of tapes that will be used records for at least sixty minutes, one dozen are purchased and examined to determine if they do record for sixty minutes. The results of the recording test in minutes show a mean of 61.28 and standard deviation of 3.868 . The professor assumes that the playing time is normally distributed. Construct an 80-percent confidence interval for the mean recording time employing these data. ___________________ _ to ___________________ _
 Fill in the blank(s) with correct word

[IRincones]

Answer to Question 1

1.30; 3.18

Answer to Question 2

59.758; 62.802