Question

At 9:00 on Saturday morning, two bicyclists heading in opposite directions pass each other on a bicycle path.The bicyclist heading north is riding 4 km/hour faster than the bicyclist heading south. At 10:15, they are 40 km apart. Find the two bicyclists’ rates.

Answer 1

let x be the speed of bicyclist A (heading north)

y be the speed of bicyclist B (heading south)

since A is 5km/hr faster than B

x = y + 5 -----equation 1

time = 9 to 10:45 = 1.75hours since the distance is 47.25km then,

x(1.75) + y(1.75) = 47.25 ---equation 2

substitute equation 1 to 2 (y+5)(1.75) + 1.75y

= 47.25 1.75y +8.75 + 1.75y

= 47.25 3.5y

= 47.25 - 8.75 3.5y

= 38.5

y = 11km/hr

substitute to equation 1

x = y + 5 x

= 11 + 5 x

= 16km/hr