Multiple choice

With a uniform speed a car covers the distance in $8$ hours. Had the speed been increased by $4$ km/hr the same distance could have been covered in $\displaystyle 7\frac{1}{2}$ hours. What is the distance covered ?

  1. $420$ km
  2. $480$ km
  3. $640$ km

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let distance be D and speed be S. D = 8S. Also, D = (S + 4) * 7.5. Equating the two: 8S = 7.5S + 30. This gives 0.5S = 30, so S = 60 km/hr. The distance D = 8 * 60 = 480 km.

AI explanation

Let the uniform speed be x km/hr; using the formula distance equals speed multiplied by time, the equation for the two scenarios is 8x equals 7.5 times (x plus 4). Solving the equation gives 8x equals 7.5x plus 30, so 0.5x equals 30, making the original speed 60 km/hr. The distance covered is 8 hours multiplied by 60 km/hr, which equals 480 km. The result is 480 km.

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