SOLUTION: Over a distance of 240km, the average speed of a train is 20km/h faster than that of a car. It takes the car 30 minutes longer to cover the same distance. What is the speed of the
Algebra.Com
Question 536716: Over a distance of 240km, the average speed of a train is 20km/h faster than that of a car. It takes the car 30 minutes longer to cover the same distance. What is the speed of the car and the speed of the train?
Thank you for any help:)
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
speed of car = x
speed of train = x+20
d=240
t=d/r
time car - time train = 1/2 hour
(240/x)-240/(x+20)=1/2
LCD = x(x+20)
240(x+20)-240x= x(x+20)/2
240x+4800-240x=(x^2+20x)/2
9600=x^2+20x
x^2+20x-9600=0
Find the roots of the equation by quadratic formula
a= 1 ,b= 20 ,c= -9600
b^2-4ac= 400 + 38400
b^2-4ac= 38800
x1=( -20 + 196.98 )/ 2
x1= 88.49 88 43/88
x2=( -20 -196.98 ) / 2
x2= -108.49
Ignore negative value
car speed = 88.49 mph
RELATED QUESTIONS
Over a distance of 120 km , the average speed of a train 40 kmh faster than the speed of... (answered by josgarithmetic)
Over a distance of 120 km , the average speed of a train 40 kmh faster than the speed of... (answered by josgarithmetic,mananth)
to travel a distance of 120km, a car takes 40 minutes faster than a bus. if a car travels (answered by richwmiller)
What is the speed of a car that has travelled 20km in 30 minutes? (answered by jhaashok630)
To travel a distance of 120 km, a car takes 40 minutes less than a bus. If the car... (answered by richwmiller)
A car takes 2 hours to travel a certain distance between two cities. If the speed of... (answered by richwmiller)
James travels 550km by car and returns the same distance by train. The car travels 25km/h (answered by josgarithmetic,MathTherapy)
Over a distance of 120 km, the average speed of a train is 40km/h faster than that of a... (answered by scott8148)
In the time that it takes one car to travel 93 km, a second car travels 111 km. If the... (answered by ankor@dixie-net.com)