Hypothesis Test(Stat)

IdRatherSleep

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"The mean length of a work week for the population of workers was reported to be 39.2 hours. Suppose that we would like to take a current sample of workers to see whether the mean length of a work week has changed from the previously reported 39.2 hours."
1.- State the hypothesis that will help us determine whether a change occurred in the mean length of a work week?
2.-Suppose a current sample of 112 workers provided a sample mean of 38.5 hours. Use a population standard deviation of 4.8 hours. What is the p value?

I have no idea how to do this problem, I would really appreciate if someone could at least answer the first question. Thanks and I hope you can help me.
 
For the first part, the claim is "the mean is different from 39.2".

Can you state the null and alternative hypotheses from this statement?.

You can use:

\(\displaystyle \L\\z=\frac{\bar{x}-{\mu}}{\frac{\sigma}{\sqrt{n}}}\)

to find your p-value.
 
What I don't get if this is an upper tail test or two tail test? Would the hypothesis be:
Null: Mean equal or less than 39.2
Alternative: Mean greater than 39.2
 
I'm thinking two-tail because they're asking for any change in the mean, which implies "not equal to".

\(\displaystyle \L\\H_{0}:{\mu}=39.2\)

\(\displaystyle \L\\H_{0}:{\mu}\neq{39.2}\)
 
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