(C) If 5% of all vehicles travel less than 40 In / h and 10% travel more than 70 m/h, what are the mean and standard deviation of the vehicle speed? Solution. We observe that (I) (Am(:19) = 0.05, (I) (mfg) = 0.9. Inverting both equations, we get a system of equations 40712 = (D'l(0.05) = 1.645, 70 _ _ TH _