Hello All, I'm struggling with this homework. I've plugged it into the Z table and haven't gotten the answers... I got this far: 66-64/(0.5/sqrt20) = 1.12. Z score = 0.0367 1.

The average speed of all vehicles on a highway is = 64 mph with a standard deviation of = 5 mph.

A random sample of 20 vehicles is clocked.What is the probability that the sample mean will exceed 66 mph?

2.

In the previous question what fraction of sample means from samples of n = 20 vehicles fall within 1 mph from the population mean speed?

3.

If you doubled the sample size in the previous question, what fraction of the sample means would fall within 1 mph from the population mean speed?

4.

In the previous question where n = 40, the middle interval which includes the 95% of the mean speed from samples of n = 40 vehicles is,

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