91.

1. Cost function

2. Revenue function

3. Selling price of x shirts after sale tax

4. Profit function

93.

1. $P(x)=20x-350$

2. $P(20)=50;$ profit made after 20 radios were sold

3. 43

4. $(R\circ x)(C)=5C-1,750.$ The function represents the revenue in terms of the cost C.

95.

1. $f(x)=0.7x$

2. $g(x)=x-5$

3. $(g\circ f)(x)=0.7x-5$

4. $(f\circ g)(x)=0.7(x-5)$

5. $1.50

97.

1. $f(x)=1.1x;g(x)=x+8$

2. $(f\circ g)(x)=1.1x+8.8;$ a final test score, which originally was x, after adding 8 points and then ­increasing the score by 10%

3. $(g\circ f)(x)=1.1x+8;$ a final test score, which originally was x, after increasing the score by 10% and then adding 8 points

4. 85.8 and 85.0

5. No

6. 1. 3.82

   2. 4.55

99.

1. $f(x)=\pi x^2$

2. $g(x)=\pi {(x+30)}^2$

3. The area between the fountain and the fence

4. $16,052

101.

1. $(f\circ g)(t)=\pi {(2t+1)}^2$

2. $A(t)=\pi {(2t+1)}^2$

3. They are the same.