The Next Questions Are Based on the Following Information

Essay

The Next Questions Are Based On The Following Information:
Research and development has designed a ball point pen so that the true average writing lifetime under controlled conditions (involving the use of a writing machine)is at least 12 hours.A random sample of 18 pens is selected,the writing lifetime of each is determined,and a normal probability plot of the resulting data supports the use of a one-sample t test.
-A company produces electrical devices operated by a thermostatic control.According to the engineering specifications,the standard deviation of the temperature at which these controls actually operate should not exceed 2.0 degrees Fahrenheit.For a random sample of 25 of these controls,the sample standard deviation of operating temperatures was 2.36 degrees Fahrenheit.Stating any assumptions you need to make,test at the 5% level the null hypothesis that the population standard deviation is at most 2.0 against the alternative that is bigger.