Economics and finance. some of the variables that affect the monthly payment of a new-car loan are the total amount borrowed, the interest rate, and the length of the loan. during the fourth quarter of 2012, the mean length of a new-car loan was 65 months, a record high according to experian. suppose the length of a new-car loan is approximately normal with standard deviation nine months. (a) what is the probability ( ±±0.0001) that a new-car loan is for at most 54 months? p(x⩽54)p(x⩽54) =