SOLUTION: a sportsman covered 15km on a bicycle at a uniform speed.if he increased his speed by 2km/h, he would have derived at a destination 1/4 hour earlier. find the original speed?

Question 840890: a sportsman covered 15km on a bicycle at a uniform speed.if he increased his speed by 2km/h, he would have derived at a destination 1/4 hour earlier. find the original speed?
Answer by hamsanash1981@gmail.com(151) (Show Source): You can put this solution on YOUR website!
Let he original speed be x and differenc in time is 1/4. then increase in speed by 2 will be x+2
time taken = distance / speed
original time taken = 15/x
time taken after increase in speed by 2 km/hr to cover the same distance = 15/x+2
difference in time = 1/4
15/x-15/(x+2)=1/4
(15(x+2) - 15x)/x(X+2) = 1/4
4(15(x+2-x)=x^2+2x
120 = x^2 +2x
x^2+2X -120 = 0
factorizing above equation we get
(x+12)(x-10)=0
X=-12 X=10
Negotiating negative we have x = 10
Therefore the original speed is 10 km/hr
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