Biostatistics question.

Question

You have just bought a new car that claims to get a highway efficiency of 31 miles per gallon. Of course, your mileage will "vary". If you had to guess, would you expect the interquartile range (IQR) of gas mileage attained by all cars like yours to be 30mpg, 3mpg or 0.3 mpg? why?

Answer 1

If 50% = 31, is it safe to assume 25% = 16 and 75%=62?  In that case, IQR = Q3-Q1 = approximately 30mpg.