SOLUTION: the time, t, required to drive a certain distance varies inversely with speed, r. If it takes 12 hours to drive the distance at 60 miles per hour, how long will it take to drive th

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: the time, t, required to drive a certain distance varies inversely with speed, r. If it takes 12 hours to drive the distance at 60 miles per hour, how long will it take to drive th      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 965811: the time, t, required to drive a certain distance varies inversely with speed, r. If it takes 12 hours to drive the distance at 60 miles per hour, how long will it take to drive the same distance at 85 miles per hour?
about 7.08 hours
about 5.00 hours
about 1.42 hours
about 8.47 hours
Found 2 solutions by checkley77, macston:
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
D=RT
D=60*12
D=720
720=85T
T=720/85
T=8.47 HOURS.

Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
d=a certain distance
d=rt Since distance at each speed is the same:
rate(60mph) x time@60mph = rate(95mph) x time@85mph
.
%2860mph%29%2812hrs%29=%2885mph%29t where t=time at 85 mph
720+miles=85t+mph Divide each side by 85 mph.
8.47+hours=t
ANSWER: It would take 8.47 hours to dive the same distance at 85 mph that it takes 12 hours to drive at 60 mph