Thank you for posting your question here at brainly. I hope the answer will help you. Feel free to ask more questions here. Below are the answers:
1a: 
(1.6 * 60) = growth per hour, GPH 
(GPH * 24) = Growth per day. 
1b: 
1N = 101.971621g (let's say 102g) 
so 0.15 * 102 = increase in grams, IIG 
IIG * 1000 = increase in milligrams, IIM 
IIM / 1.6 = how many minutes to reach that weight.