#### To determine

**(a)**

**To state:**

The Net Change Theorem

#### Answer

The integral of a rate of change is the net change:

*∫abF'(x)=Fb-F(a)*

#### Explanation

**The Net Change Theorem:**

The integral of a rate of change is the net change:

*∫abF'(x)=Fb-F(a)*

**Conclusion:**

The integral of a rate of change is the net change:

*∫abF'(x)=Fb-F(a)*

#### To determine

**(b)**

**To explain:**

What does *∫t1t2r(t)dt* represent?

#### Answer

The change in the amount of water in the reservoir, between time *t1* to *t2*

#### Explanation

*∫t1t2r(t)dt* is the change in the amount of water in the reservoir, between time *t1* to *t2*

**Conclusion:**

The given expression represents the change in the amount of water in the reservoir, between time *t1* to *t2*