1. A manufacture of tires wants to advertise a mileage interval that excludes no more than 10% of the mileage on tires he sells. All he knows is that, for a large number of tires tested, the mean mileage was 25,000 miles, and the standard deviation was 4000 miles. What interval would you suggest?
2. Five cards are drawn from a standard 52-card playing deck. What is the probability that all 5 cards will be of the same suit?