A car covers a certain distance in 7 hours with a uniform speed. The same distance could have been covered in 6 hours if the speed of the car was increased by 10 Km/h. What is the distance covered?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 420 Km
The distance is the same both times, so speed = distance ÷ time gives the two speeds in terms of the distance \(d\), and they differ by the given 10 km/h.
Usual speed \(\displaystyle =\frac{d}{7}\) km/h
Increased speed \(\displaystyle =\frac{d}{6}\) km/h
\(\displaystyle \frac{d}{6}-\frac{d}{7}=10\)
\(\displaystyle \frac{7d-6d}{42}=10\), so \(d=420\) km