Multiple choice

A person drives his car for $3$ hours at a speed of $40$ km/hr and for $4.5$ hours at a speed of $60$ km/hr. At the end of it, he finds that he was covered $\displaystyle \frac {3}{5}$ of the total distance. What is the uniform speed with which he should further drive to cover the remaining distance in $4$ hours?

  1. $35$ km/hr
  2. $20$ km/hr
  3. $65$ km/hr
  4. $50$ km/hr
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Distance 1 = 3 * 40 = 120 km. Distance 2 = 4.5 * 60 = 270 km. Total covered = 390 km. This is 3/5 of total, so total = 390 * 5/3 = 650 km. Remaining = 650 - 390 = 260 km. Speed = 260 / 4 = 65 km/hr.

AI explanation

The distance covered in the first part of the trip is calculated as (3 hours times 40 km/hr) plus (4.5 hours times 60 km/hr), totaling 390 km. Since 390 km represents 3/5 of the total distance, the total distance is 390 multiplied by 5/3, which equals 650 km; the remaining distance is 650 minus 390, or 260 km. Using the formula speed equals distance divided by time, the required speed to cover the remaining 260 km in 4 hours is 260 divided by 4, yielding 65 km/hr. The result is 65 km/hr.

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