2014 · Q33
A man rides one-third of the distance from A to B at the rate of x km/hr and the remainder at the rate of 2y km/hr. If he had travelled at a uniform rate of 6z km/hr, he could have ridden from A to B and back again in the same time. Which one of the following is correct?
Elementary MathematicsTime, Speed and Distance
- Az = x + y
- B3z = x + y
- C1/z = 1/x + 1/y
- D1/2z = 1/x + 1/y
Explanation
One-way time = d/(3x) + d/(3y); round trip at 6z takes d/(3z). Equating gives 1/z = 1/x + 1/y.