Average leaf width, w (in mm), in tropical australia1 is a function of the average annual rainfall, r (in mm), so w=f(r). we have f′(1500)=0.0218. (a) what are the units of the 1500? the units of 1500 are mm (of rain)/year. mm (of leaf width)/year. mm (of rain)/mm (of leaf width). mm. mm (of leaf width)/mm (of rain). (b) what are the units of the 0.0218? the units of 0.0218 are mm (of rain)/mm (of leaf width). mm (of rain)/year. mm (of leaf width)/year. mm. mm (of leaf width)/mm (of rain). (c) about how much difference in average leaf width would you find in two forests whose average annual rainfalls are near 1500 mm but differ by 210 mm? round your answer to 2 decimal places. the difference in leaf width is mm. 1 h. shugart, terrestrial ecosystems in changing environments (cambridge: cup, 1998), p. 145.