Question

an aeroplane flies 200 km with uniform speed of 300 km per hour and then another 200 km with a uniform speed of 240 km per hour calculate the average speed of the aeroplane

Answer 1

total distance=200+200=400 km
time taken for first 200 km=200/300=2/3 hr
time taken for second 200 km=200/240=5/6 hr
total time=2/3+5/6=9/6=3/2=1.5 hr
average speed=total distance/total time
=400/1.5
=800/3=266.67kmph

Answer 2

average speed=total distance/total time

first distance=200km

first time=200/300

. =2/3

second distance=200

second time=5/6

total distance=400

total time= 2/3+5/6

. =3/2=1.5

average speed=

\begin{gathered}\frac{400}{1.5} \\ = \frac{4000}{15} \\ = 266.666....\end{gathered}

1.5

400

=

15

4000

=266.666....

=266.667 km/h