SOLUTION: A bicycle trip of 90 miles would have taken an hour less if the average speed had been increased by 3 mi/h. Find the average speed of the bicycle.

Question 519968: A bicycle trip of 90 miles would have taken an hour less if the average speed had been increased by 3 mi/h. Find the average speed of the bicycle.
Answer by mananth(16949) (Show Source): You can put this solution on YOUR website!
let speed be x
t=d/r
time with original speed - time with increased speed = 1
90/x-90/(x+3)=1
LCD=x(x+3)
multiply by LCD
90(x+3)-90x=x(x+3)
90x+270-90x=x^2+3x
x^2+3x-270=0
x^2+18x-15x-270=0
x(x+18)-15(x+18)=0
(x+18)(x-15)=0
x=15 ignoring negative value
speed = 15 mph
m.ananth@hotmail.ca
RELATED QUESTIONS
A bicycle trip of 90 miles would have taken an hour less if the average speed had been... (answered by mananth)

A bicycle trip of 120 miles would have taken 3 hours less if the average speed had been... (answered by checkley77,themathprof)

A bus trip of 90 miles would have taken an hour less if the average speed had been... (answered by josmiceli)

Car traveled 504 mi averaging a certain speed. If the car had gone 7 mph faster, the trip (answered by lmeeks54)

Consuela biked 20 miles. If she had increased her average speed by 4 miles per hour, the... (answered by Boreal)

Imogene's car traveled 210 mi averaging a certain speer. If the car had gone 5mph faster, (answered by stanbon)

Imogene's car traveled 280 mi averaging a certain speed. If the car had gone 5 mph... (answered by mananth)

a man made a trip of 432 miles by car. if the average speed had been 6 miles per hour... (answered by mananth)

a car travels at a constant speed for 450km if the average speed was increased by 15km/h... (answered by josgarithmetic,MathTherapy)