SOLUTION: Imogene's car traveled 420 mi averaging a certain speed. If the car had gone 10 mph faster, the trip would have taken 1 hour less. Find the average speed.

Question 974549: Imogene's car traveled 420 mi averaging a certain speed. If the car had gone 10 mph faster, the trip would have taken 1 hour less. Find the average speed.
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39618) (Show Source): You can put this solution on YOUR website!
generalizing the description with variables,
Imogene's car traveled d miles averaging a certain speed. If the car had gone k mph faster, the trip would have taken h hour less. Find the average speed, r.

_______________________rate______________time______________distance
Certain________________r_________________t_________________d
IfFaster_______________r+k_______________t-h_______________d

KNOWN
h, k, d

UNKNOWN
r, t

BASIC RELATIONSHIP, EQUATION
RT=D relating rate, time, distance

SYSTEM OF EQUATIONS

Solve the system for r and t.
Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!

Imogene's car traveled 420 mi averaging a certain speed. If the car had gone 10 mph faster, the trip would have taken 1 hour less. Find the average speed.

Average speed:
RELATED QUESTIONS
Car traveled 504 mi averaging a certain speed. If the car had gone 7 mph faster, the trip (answered by lmeeks54)
Imogene's car traveled 210 mi averaging a certain speer. If the car had gone 5mph faster, (answered by stanbon)
Imogene's car traveled 576 mi averaging a certain speed. If the car had gone 8 mph faster (answered by josmiceli)
Imogene's car traveled 360 mi averaging a certain speed. If the car had gone 5 mph... (answered by ikleyn)
car traveled 432miles averaging a certain speed. If the car had gone 6 mph faster, the... (answered by josmiceli,josgarithmetic)
Imogene's car traveled 770 mi averaging a certain speed. If the car has gone 7 mph... (answered by josmiceli)
Imogene's car traveled 660 mi averaging a certain speed. If the car had gone 6 mph... (answered by ikleyn)
Gene's car traveled 210 miles averaging a certain speed. If the car had gone 5 mph... (answered by mananth)
Imogene's car traveled 624 miles averaging a Certain speed. If the car had gone 4 mph... (answered by josmiceli)