Using Formulas - Pre Algebra

1. Use $P = 2l + 2w$ to find the perimeter of a rectangle with $l = 8$ and $w = 3$.

   22 units. $16 + 6 = 22$.

2. Use $A = s^2$ to find the area of a square with side 9 meters.

   81 square meters. $9^2 = 81$.

3. Use $F = \frac{9}{5}C + 32$ to convert $25$ degrees Celsius to Fahrenheit.

   77 degrees Fahrenheit. $\frac{9}{5} \cdot 25 = 45$, and $45 + 32 = 77$.

4. In the prism volume formula $V = Bh$, what does $B$ represent?

   The area of the prism's base, not a side length.

5. What kind of units does a volume have?

   Cubic units, such as cubic centimeters, because it multiplies three lengths.

6. Use $A = lw$ to find the area of a rectangle 7 units long and 4 units wide.

   28 square units. $7 \times 4 = 28$.

7. Use $I = Prt$ to find the simple interest on 200 dollars at a rate of $r = 0.05$ per year for 2 years.

   20 dollars. $I = 200(0.05)(2) = 20$.

8. Use $A = \frac{1}{2}h(b_1 + b_2)$ for a trapezoid with bases 6 and 10 and height 4.

   32 square units. $\frac{1}{2} \cdot 4 \cdot 16 = 32$.

9. Use $d = rt$ to find the distance traveled at 45 miles per hour for 3 hours.

   135 miles. $45 \times 3 = 135$.

10. In the trapezoid formula $A = \frac{1}{2}h(b_1 + b_2)$, what do $b_1$ and $b_2$ represent?

    The lengths of the two parallel sides (the bases). $h$ is the perpendicular distance between them.

11. Use $A = \frac{1}{2}bh$ to find the area of a triangle with base 10 and height 6.

    30 square units. $\frac{1}{2} \cdot 10 \cdot 6 = 30$.

12. Use $V = lwh$ to find the volume of a box 3 by 4 by 5 centimeters.

    60 cubic centimeters. $3 \cdot 4 \cdot 5 = 60$.

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