Given: Kuldeep completes one round in 6 minutes at the speed of 10 km/h and completes one round in 4 minutes. Concept Used: The distance traveled or covered by a person or an object in unit time, is called its speed. The unit of speed is m/s or km/h or kmph. Calculation: Speed of Kuldeep on first day of the month = Distance Covered/Time Taken ⇒ S1 = D/T1 ⇒ D = S1 × T1 ⇒ D = 10 × (6/60) ⇒ D = 60/60 ⇒ D = 1 km Now, Speed of Kuldeep on last day of the month = Distance Covered/Time Taken ⇒ S2 = D/T2 ⇒ S2 = 1/(4/60) ⇒ S2 = 60/4 ⇒ S2 = 15 km/h Now, the improvement in Kuldeep’s speed = (S2 - S1) ⇒ 15 – 10 ⇒ 5 km/h So, Increase in Kuldeep’s speed in m/s = (S2 - S1) × (5/18) ⇒ 5 × (5/18) ⇒ 25/18 m/s ∴ Kuldeep increased his speed by 25/18 m/s in one month. Important Points To convert a speed given in km/h to m/s, multiply the speed by 5/18 To convert a speed given in m/s to km/h, multiply the speed by 18/5 To convert a speed given in m/s to m/min, multiply the speed by 60 To convert a speed given in m/min to m/s, divide the speed by 60 Mistake Points The unit of speeds given in the question are in km/h and the answer is asked in m/s. So, make sure you do the proper unit conversion to arrive at the correct answer.