9.1 Measurement and the united states system  (Page 2/2)

Convert 11 yards to feet.

Looking in the unit conversion table under length , we see that $1\text{yd}=\text{3 ft}$ . There are two corresponding unit fractions, $\frac{\text{1 yd}}{\text{3 ft}}$ and $\frac{\text{3 ft}}{\text{1 yd}}$ . Which one should we use? Look to see which unit we wish to convert to. Choose the unit fraction with this unit in the numerator . We will choose $\frac{\text{3 ft}}{\text{1 yd}}$ since this unit fraction has feet in the numerator. Now, multiply 11 yd by the unit fraction. Notice that since the unit fraction has the value of 1, multiplying by it does not change the value of 11 yd.

$\begin{array}{cccc}\hfill 11\text{yd}& =& \frac{\text{11}\text{yd}}{1}\cdot \frac{3\text{ft}}{\text{1yd}}\hfill & \text{Divide out common units.}\hfill \\ & =& \frac{11\cancel{\text{yd}}}{1}\cdot \frac{3\text{ft}}{1\cancel{\text{yd}}}\hfill & \text{(Units can be added, subtracted, multiplied, and divided, just as numbers can.)}\hfill \\ & =& \frac{11\cdot 3\text{ft}}{1}\hfill & \\ & =& 33\text{ft}\hfill & \end{array}$

Thus, $11\text{yd}=33\text{ft}$ .

Convert 36 fl oz to pints.

Looking in the unit conversion table under liquid volume , we see that $\text{1 pt}=\text{16 fl oz}$ . Since we are to convert to pints, we will construct a unit fraction with pints in the numerator.

$\begin{array}{cccc}\hfill 36\text{fl oz}& =\hfill & \frac{36\text{fl oz}}{1}\cdot \frac{1\text{pt}}{16\text{fl oz}}& \text{Divide out common units.}\hfill \\ & =& \frac{36\cancel{\text{fl oz}}}{1}\cdot \frac{1\text{pt}}{16\cancel{\text{fl oz}}}\hfill & \\ & =& \frac{36\cdot \text{1 pt}}{16}\hfill & \\ & =& \frac{\text{36 pt}}{16}\hfill & \text{Reduce.}\hfill \\ & =& \frac{9}{4}\text{pt}\hfill & \text{Convert to decimals:}\frac{9}{4}=2.25.\hfill \end{array}$

Thus, $\text{36 fl oz}=\text{2}\text{.}\text{25 pt}$ .

Convert 2,016 hr to weeks.

Looking in the unit conversion table under time , we see that $\text{1wk}=\text{7da}$ and that $1\text{da}=\text{24 hr}$ . To convert from hours to weeks, we must first convert from hours to days and then from days to weeks. We need two unit fractions.

The unit fraction needed for converting from hours to days is $\frac{\text{1 da}}{\text{24 hr}}$ . The unit fraction needed for converting from days to weeks is $\frac{\text{1 wk}}{\text{7 da}}$ .

$\begin{array}{cccc}\hfill \mathrm{2,016}\text{hr}& =& \frac{\mathrm{2,016}\text{hr}}{1}\cdot \frac{1\text{da}}{24\text{hr}}\cdot \frac{1\text{wk}}{7\text{da}}\hfill & \text{Divide out common units.}\hfill \\ & =& \frac{\mathrm{2,016}\cancel{\text{hr}}}{1}\cdot \frac{1\cancel{\text{da}}}{24\cancel{\text{hr}}}\cdot \frac{1\text{wk}}{7\cancel{\text{da}}}\hfill & \hfill \\ & =& \frac{\mathrm{2,016}\cdot 1\text{wk}}{24\cdot 7}\hfill & \text{Reduce.}\hfill \\ & =& 12\text{wk}\hfill & \end{array}$

Thus, $\text{2,016 hr}=\text{12 wk}$ .