The mean number of gallons of gasoline pumped per customer at Ray's Marathon Station is 9.5 gallons with a standard deviation of 0.75 gallons. The median number of gallons pumped is 10.0 gallons. The arithmetic mean amount of time spent by a customer in the station is 6.5 minutes with a standard deviation of 2 minutes.

a. According to chebyshev's Theorem, what proportion (percent) of the customers spend between 3.30 minutes and 9.70 minutes at the station?

b. According to the Empirical Rule, what proportion of the customers pump between 8.00 gallons and 11.00 gallons?