Multiple choice

A plane left 2 h later than the scheduled time and in order to reach its destination 2400 km away in time, it had to increase its speed by 33.33% over its usual speed. Find the new increased speed?

  1. 300 kmph

  2. 200 kmph

  3. 100 kmph

  4. 400 kmph
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D Correct answer
Explanation

Let original speed be v. Time taken = 2400/v. New speed = 1.333v = 4/3 v. New time = 2400 / (4/3 v) = 1800/v. Difference = 2400/v - 1800/v = 2. 600/v = 2, so v = 300. New speed = 1.333 * 300 = 400.

AI explanation

Using the formula Time equals Distance divided by Speed, let the usual speed be x and the increased speed be 4x/3 since it is increased by 33.33 percent. The difference in time is 2 hours, so 2400/x minus 2400/(4x/3) equals 2, which simplifies to 2 hours. Solving 2400/x equals 8 gives the usual speed x as 300 kmph. The new increased speed is 4/3 of 300, which is 400 kmph.

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