Multiple choice

A motorcycle does a journey from city A to city B in 10 hrs, the first half of the distance at 21 km/hr and the second half of the distance at 24 km/hr. Find the distance between the two cities?

  1. 220 km

  2. 240 km

  3. 210 km

  4. 224 km
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let total distance be 2D. Time = D/21 + D/24 = 10. D(8+7)/168 = 10. D(15/168) = 10. D = 1680/15 = 112. Total distance = 2D = 224 km.

AI explanation

Let the total distance be x km, meaning the first half is x/2 km and the second half is x/2 km. Using the time formula where time equals distance divided by speed, the equation becomes (x/2)/21 + (x/2)/24 = 10. Solving this, x/42 + x/48 = 10, gives a combined denominator where 8x + 7x = 3360, simplifying to 15x = 3360. Therefore, the total distance x is 224 km.

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