Question

PT. Usha runs for 10 minutes at a speed of 18 kilometre per hour for 45 minutes at a speed of 27 kilometre per hour and 45 minutes at a speed of 36 km per hour. Calculate her average speed.

Answer 1

Answer:

8.3m/s

Explanation:

Usha runs

Time (t1) = 10min => 600s

Speed (v1) = 18 km/h or 18 × 5/18 => 5m/s

Distance (s1) = 5×600 = 3000m

Time (t2) = 45 min => 2700s

Speed (v2) = 27 km/h or 27 × 5/18 => 7.5m/s

Distance (s2) = 7.5 × 2700 = 20250m

Time (t3) = 45min => 2700s

Speed (v3) = 36 km/h => 36×5/18 => 10m/s

Distance (s3) = 2700 × 10 = 27000m

Average Speed (Vav) = Total Distance/Total Time

➞ Vav = 3000+20250+27000/600+2700+2700

➞ Vav = 50250/6000

➞ Vav = 8.3 m/s

Average Speed of Usha will be 8.3m/s