In a simple random sample of 80 automobiles registered in Jland , 28 of them were found to have emission levels that exceed a state standard. let p be the proportion of all automobiles in Jland hat have emission levels that exceed the state standard.
a) What proportion of automobiles in the sample had emission levels that exceed the standard?
b) Obtain a point estimate for p.
c) Using the classical confidence interval ( not score) construct a 98% confidence interval for p.
d) Using the classical confidence interval ( not score) construct a 99.9% confidence interval for p.
e) Using your estimate from part b as p, calculate the probability that between 3 and 5 ( 3?x?5) of the next 10 automobilies inspeted have emission levels that exceed the state standard.
f) How many automobilies would have to be tested to guarantee that a 98% confidence interval will have a length of no more than .20?