Carl has to travel a certain distance. After he has travelled 40 kilometres, he increases his speed by 2 kilometres per hour. If he had travelled with this increased speed during the whole of his journey, he would have arrived 40 minutes earlier at his destination. On the other hand, if he had continued with his original speed, he would have arrived 20 minutes later.

How far did Carl have to travel?

How would this go.

Z=Total Distance

X=Initial speed

The info provided gives the following simultaneous equations

40/X +(Z-40)/(X+2)-2/3=Z/(X+2)

40/X + (Z-40)/(X+2) +1/3=Z/X

Solving these gives a quadratic

(2x-20)(x+12)=0

Giving Initial speed as 10km and a total distance travelled of 60km.

Jim

Posted by Jim on 2006-12-26 17:31:57