Multiple choice

A person rode one-third of a journey at 60 km/hr, one-third at 50 km/hr and the rest at 40 km/hr. Had the person ridden half of the journey at 60 km/hr and the rest at 40 km/hr, he would have taken 4 minutes longer to complete the journey. What distance did the person ride to?

  1. 180 km

  2. 210 km

  3. 240 km

  4. 300 km
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let total distance be D. Time1 = (D/3)/60 + (D/3)/50 + (D/3)/40 = D/180 + D/150 + D/120 = (10D + 12D + 15D)/1800 = 37D/1800. Time2 = (D/2)/60 + (D/2)/40 = D/120 + D/80 = (2D + 3D)/240 = 5D/240 = D/48. Difference = D/48 - 37D/1800 = 4/60 hours = 1/15. Solving for D gives 240 km.

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