SOLUTION: 4. The formula s = square root of 13.5d estimates the speed s in miles per hour that a car was traveling when it applied its brakes and left a skid mark d feet long on a wet roa

Algebra ->  Rational-functions -> SOLUTION: 4. The formula s = square root of 13.5d estimates the speed s in miles per hour that a car was traveling when it applied its brakes and left a skid mark d feet long on a wet roa      Log On


   

Question 252660: 4. The formula s = square root of 13.5d estimates the speed s in miles per hour that a car was traveling when it applied its brakes and left a skid mark d feet long on a wet road. Estimate the speed of a car that left a 120-foot-long skid mark. What is the correct answer from the list below. Thank you!
about 20.75 mph
about 40.25 mph
about 60.75 mph
about 80.25 mph
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
s=sqrt(13.5d)
fortunately we don't have to convert from feet to miles.
So we just plug in the numbers
s=sqrt(1620)
s=40.2492 which is about 40.25
the formula is for wet roads and we aren't told if the road was wet so can't really apply this formula with certainty