Question

A car travelled 100 kilometres distance with a speed of 60 kmph and 200 km distance with a speed of 45 kmph . what is the average speed to cover total distance?​

Answer 1

$time \: taken \: to \: cover \: a \: distance \: of \: 100 \: km = \frac{100}{60} = > \frac{5}{3} \: hours$

$time \: taken \: to \: cover \: a \: distance \: of \:200\: km = \frac{200}{45} = > \frac{40}{9} \: hours$

$total \: distance\: covered \: by \: car = (100 + 200) = > 300 \: km$

$tota l\: time \: taken \: to \: cover \: 300 \: km = \frac{5}{3} + \frac{40}{9} = > \frac{55}{9}$

$average \: speed = \frac{total \: distance \: covered}{total \: ti me \: taken}$

$average \: speed = \frac{300}{ \frac{55}{9} } \\ = > 300 \div \frac{55}{9} \\ = > 300 \times \frac{9}{55} \\ = > 49 \: km {h}^{ - 1}$

Answer 2

Average speed is (100+200)/(100/60+200/45)

=300/(5/3+40/9)=300/(55/9)

=300*9/55=49.1 approximately