Multiple choice

A scooterist completes a certain journey in $10$ hours. He covers half the distance at $30$ km/hr and the rest at $70$ km/hr. What is the total distance of the journey?

  1. $460$ km.
  2. $500$ km.
  3. $420$ km.
  4. $560$ km.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let total distance be 2D. Time = D/30 + D/70 = 10. (7D + 3D) / 210 = 10. 10D / 210 = 10. D = 210. Total distance = 2D = 420 km.

AI explanation

Let half of the total distance be D kilometers, so the time taken for the first half is D divided by 30 and the time for the second half is D divided by 70. Using the given total time of 10 hours, we write the equation (D divided by 30) + (D divided by 70) = 10. Finding a common denominator gives (7D + 3D) divided by 210 = 10, which simplifies to 10D = 2100. Solving for D gives 210 km, meaning the total journey is 2 multiplied by 210, which equals 420 km.

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