Multiple choice

A car travelling with $\frac{5}{7}$ of its actual speed covers 42 km in 1 hr 40 min 48 sec. Find the actual speed of the car.

  1. $17\frac{6}{7}$ km/hr
  2. 25 km/hr

  3. 30 km/hr

  4. 35 km/hr

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let actual speed be v. Speed = 5/7 * v. Time = 1h 40m 48s = 1 + 40/60 + 48/3600 = 1 + 2/3 + 2/150 = 1 + 100/150 + 2/150 = 1 + 102/150 = 1.68 hours. Distance = 42 km. 5/7 * v = 42 / 1.68 = 25. v = 25 * 7 / 5 = 35 km/hr.