Question

a car covers the first half of distance between two places at the speed of 40 km per hour and second half 60 kilometre per hour what is the average speed​

Answer 1

SOLUTION

Let the distance covered be d

speed in the first half d/2 = 60kmph

speed in the first half d/2 = 60kmphspeed in the second half d/2= 40kmph.

Now, let the time taken by the car in first half = t1.

$t1 = \frac{ \frac{d}{2} }{60} = \frac{d}{120}$

Now let the time taken by the car in 2nd half = t2

$t2 = \frac{ \frac{d}{2} }{40} = \frac{d}{80}$

Average speed= Total distance/total time taken

$\frac{ \frac{d}{2} + \frac{d}{2} }{t1 + t2} \\ \\ = > \frac{d}{ \frac{d}{80} + \frac{d}{120} } \\ \\ = > \frac{80 \times 120}{80 + 120} = \frac{9600}{200} \\ \\ = > 48 \: kmph$

hope it helps ☺️