6.a) The equation for the estimation of hip height is h = 5f - 0.5, where h is hip height and f is foot length (in metres). The rate of change of hip height with respect to foot length will be the slope or gradient of this graph, which is 5 (so it is predicted that there is a 5m increase in hip height for each 1m increase in foot length)
b) If the back length of the average adult male Tyrannosaurus is three times its hip height then:
13f + 0.3 = 3(5f - 0.5)
13f + 0.3 = 15f - 1.5
2f = 1.8
f = 0.9m
If f = 0.9:
Hip height = 5(0.9) - 0.5
= 4.5 - 0.5
= 4 m
Back length = 3(4) = 12 m