A man running at the speed of 10 km/hr takes 7 minutes to travel a certain distance . By how much should he increase his speed (in km/hr) to cover the same distance in 5 minutes ?
Answer & explanation
Correct answer: option 2
Distance = speed × time
Time taken = 7 minutes = \(\frac{7}{60}\) hr
Speed = 10 km/hr
Distance = 10 × \(\frac{7}{60}\)
New time = 5 minutes = \(\frac{5}{60}\) hr
New speed = \(\frac{distance}{time}\) = 10 × \(\frac{7}{60}\) × \(\frac{60}{5}\)
New speed = 14 km/hr
Increase in speed = New speed - Old speed
= 14 - 10 = 4 km/hr