statistics
posted by George on .
An auto maker estimates that the mean gas mileage of its sport utility vehicle is 20 miles per gallon. A random sample of 8 such vehicles had a mean of 18 per gallon and a standard deviation of 5 miles per gallon. At á=0.05, can you reject the auto maker’s claim that the mean gas mileage of its sports
utility vehicle is 20 miles per gallon? Assume the population is normally distributed.

You can use a ttest for this problem since the sample size is small.
Using your data in the formula:
t = (18  20)/(5/√8) = ?
Finish the calculation.
Using a ttable at 0.05 level of significance for a twotailed test (the test is twotailed because the alternative hypothesis would not specify a direction) at 7 degrees of freedom (df = n  1 = 8  1 = 7), find your critical or cutoff value to reject the null. If the ttest statistic calculated above does not exceed the critical value you found in the ttable, you cannot reject the null. If the ttest statistic exceeds the critical value from the ttable, reject the null.
I hope this will help get you started. 
of 500 employee ,200 participating i n companies profit sharing plan (p),250 having major medical insurance coverage (m) and 50 find the probibility +will not be participant in either program

of 500 employee ,200 participating i n companies profit sharing plan (p),250 having major medical insurance coverage (m) and 50 participated in both program
find the probibility will not be participant in either program