According to the Fuel Economy Guide for 2016 model vehicles the combined city and highway gas mileage of the vehicles (ignoring a few outliers) is approximately Normal with mean 23.0 miles per gallon and standard deviation 4.9 mpg. 

a) The Volkswagen Beetle has a combined gas mileage of 28 mpg. What percent of all 2016 vehicles have better gas mileage than the Beetle? 

b) How high must a 2016 vehicle's gas mileage be to fall in the top 15% of all vehicles?  

c) what values are associated with the first and third quartiles of combined mpg?