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Official Paper 20: Held on 11th Nov 2020 Shift 2

Option 4 : 20 km/h

**Given:**

Distance to cover = 100 m

**Formula used:**

Distance = Speed × Time

**Concept used:**

To convert m/s to km/h then multiply with 18/5

**Calculation:**

A beats B by 10 meters or 2 seconds means B covers 10 meters distance in 2 seconds

Speed of B = 10/2 = 5 m/s

Total time is taken by B to complete 100 m race = 100/5 = 20 seconds

A takes 2 seconds less to complete the race

Time is taken by A to complete the race = 20 – 2 = 18 sec

Speed of A = 100/18 m/s = (100/18) × (18/5) = 20 km/h

**∴ The speed of A is 20 km/h**