Explanation
Given that,
Time $$t=2.5\min $$
Distance $$d=2km$$
Now, firstly for half distance
$$ v=\dfrac{d}{t} $$
$$ t=\dfrac{d}{v} $$
$$ t=\dfrac{60\times 60}{40} $$
$$ t=90\,s $$
Now, total time is
$$ t=150-90 $$
$$ t=60\,s $$
Now, the speed is
$$ v=\dfrac{1\times 60}{1} $$
$$ v=60\,km/h $$
Hence, the speed is $$60 km/h$$
Please disable the adBlock and continue. Thank you.