(a)(i) It takes 1.6 seconds to reach a height of 70 metres.
(ii) Height of stone at 5 seconds was 50 metres but after 5 seconds, d < 50 metres.
(iii) It reaches its maximum height after 2.9 seconds.~(b) From the graph, the gradient of the slope = \(\frac{AB}{BC}\)
= \(\frac{56}{2.8} = 20 m/s\)
But it is a negative slope, hence the slope = -20 m/s.

