Hey guys. The below answer to this question is completely wrong. If you divide (and you always have to make sure that your units are divided as well with the numbers) 500mL by 120mL/ hr it looks like this: 500mL / (120mL/hr) =4.17hr So, you see that 4.17 is not the number of mL's that is being infused, it is the number of hours that you will infuse 120mL/hr to achieve the 500mL total that is desired with the stated setting. The math for these 5 problems is incorrect and should be ignored.