Question

An aeroplane covers 2500 km, 1200 km and 500 km at the rate of 500 km/hr, 400 km/hr and 250 km/hr respectively. Find his average speed for the whole journey.

Answer 1

hopefully it helps you

Answer 2

for 2500 km, time needed = 2000km ÷ 500km/hr = 5hr

for 1200 km, time needed = 1200km ÷ 400km/hr = 3hr

for 500 km, time needed = 500km ÷ 250km/hr = 2 hr

total time needed = 10hr

total distance = 2500km+1200km+500km = 4200km

average speed = 4200km ÷ 10hr = 420km/hr