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

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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

In 2010

Bradley 410

Rhea 480

Marion 407

Grundy 428

Sequatchie 400

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.