SOLUTION: A car traveled 468 mi at a certain speed. If the speed had been 13 mph faster, the trip could have been made in 3 hr less time. Find the speed.

Question 839777: A car traveled 468 mi at a certain speed. If the speed had been 13 mph faster, the trip could have been made in 3 hr less time. Find the speed.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A car traveled 468 mi at a certain speed. If the speed had been 13 mph faster, the trip could have been made in 3 hr less time. Find the speed.
---------
Slower DATA:
distance = 469 miles ; rate = r mph ; time = 469/r hrs
------
Faster DATA:
distance = 469 miles ; rate = r+13 mph ; time = 469/(r+13) hrs
-----------------
Equation:
slower time - faster time = 3 hrs.
469/r - 469/(r+13) = 3 hrs
------------------------------
469r + 469*13 - 469r = 3r(r+13)
---------
3r^2 + 39r -469*13 = 0
r = 39.05.. mph
====================
Cheers,
Stan H.
--------------------
RELATED QUESTIONS
A car traveled 3276 mi at a certain speed. If the speed had been 13 mph faster, the trip (answered by mananth)

A car traveled 1950 mi at a certain speed. If the speed had been 13 mph faster, the trip (answered by josgarithmetic,ikleyn)

a car traveled 1350 mi at a certain speed. if the speed had been 9 mph faster, the trip... (answered by josgarithmetic)

a car traveled 4032 mi at a certain speed. if the speed had been 16 mph faster, the trip... (answered by lwsshak3,mananth)

Lisa traveled 1040 mi at a certain speed. If the speed had been 13 mph faster, the trip... (answered by ewatrrr)

a car traveled 1520 miles at a certain speed. if the speed had been 19 mph faster, the... (answered by ankor@dixie-net.com)

A car traveled 1800 mi at a certain speed. If the speed had been 12 mph faster, the trip... (answered by josgarithmetic,MathTherapy)

A car traveled 1280 miles at a certain speed. If the speed had been 16 mph faster, the... (answered by stanbon)

A car traveled 960 miles at a certain speed. If the speed had been 12 mph faster, the... (answered by ankor@dixie-net.com)