I would like to elaborate on the answer to the second question, since the first answer is actually option a. Why? The question asks for a parametric equation, not set, so it would be choice a.
Home Water Works says that in most homes, showers are the third-largest user of water after toilets and clothes washers. The average American shower water usage is 17.2 gallons with the average shower length being 8.2 minutes. The average flow rate is 2.1 gallons per minute.
