Posted by Jackie on .
Along a straight road through town, there are three speed-limit signs. They occur in the following order: 66 , 31 , and 19 mi/h, with the 31 -mi/h sign located midway between the other two. Obeying these speed limits, the smallest possible time tA that a driver can spend on this part of the road is to travel between the first and second signs at 66 mi/h and between the second and third signs at 31 mi/h. More realistically, a driver could slow down from 66 to 31 mi/h with a constant deceleration and then do the same thing from 31 to 19 mi/h. This alternative requires a time tB. Find the ratio tB/tA