I had to miss my last 2 calc classes and now i'm completely lost on my homework. I posted two problems, the first i don't even know how to begin to start (i'm really confused as to find the hypothesis) and the second i was able to determine the mean and standard deviation (part a) but after that i'm lost. If anyone is able to offer some step by step assistance i'd really appreciate it.
A producer of various kinds of batteries has been producing "D" size batteries with a life
expectancy of 87 hours. Due to an improved production process, management believes that there has
been an increase in the life expectancy of their "D" size batteries. A sample of 36 batteries showed an
average life of 88.5 hours. Assume from past information that it is known that the standard deviation of
the population is 9 hours.
a. Give the null and the alternative hypotheses.
b. Compute the standardized test statistic.
c. At 1% (α = .01) significance level test management's belief. State your conclusion
The Department of Economic and Community Development (DECD) reported that in 2009 the
average number of new jobs created per county was 450. The department also provided the following
information regarding a sample of 5 counties in 2010.
County New Jobs Created
a. Compute the sample average and the standard deviation for 2010.
b. We want to determine whether there has been a significant decrease in the average number
of jobs created. Provide the null and the alternative hypotheses.
c. Compute the standardized test statistic. Assume the population is normally distributed.
d. At 5% (α = .05) significance, test the hypotheses. State your conclusion.