posted by ree .
The tires are also tested for failure during a road test where they are subjected to road hazards. A test of 600 tires resulted in the failure of 30 tires.
a) Find a 95% confidence interval on the proportion of failures for the new formula of of rubber.
b) The proportion of failures for the existing line of tires is p=.1 . Can we conclude the new line of tires is better? (use alpha=.05)