Question

during the first half of a journey by a body, it travels with a speed of 40km/hr and in the next half it travels woth a speed of 20km/hr. Calculate the average speed of the whole journey.

Answer 1

Half distance=x(let)
Other half distance=x(let)
speed(v)=40km/hr(For first half)
speed(v)=20km/hr(For second half)
t(For first part)=xhr/40km
t(For second part)=xhr/20km
So Average speed for the whole journey is =s/t
=x+x/x/40+x/20 km/hr
=2x/x+20x/40 km/hr
=80x/21x km/hr
=3.81 km hr⁻¹

Answer 2

$\huge\underline\mathfrak{Solution:-}$

Speed during first half= 40 km/hr

Speed during second half= 20 km/hr

$\underline\textsf{Average\:Speed:-}$

$\frac{v1 + v2}{2} = \frac{40 + 20}{2} = \frac{60}{2}$

30km/hr

$\textsf{Answer:-30km/hr}$