To determine how many floor boards, each 2-1/4 inches wide, are needed to cover a floor that is 15 feet wide, we can follow these steps:
1. Convert the width of the floor from feet to inches:
- Since there are 12 inches in a foot, we multiply the width in feet by 12.
- [tex]\( 15 \text{ feet} \times 12 \text{ inches/foot} = 180 \text{ inches} \)[/tex]
2. Determine the width of one floor board in inches:
- Each floor board is 2-1/4 inches wide, which can be written as [tex]\( 2.25 \text{ inches} \)[/tex].
3. Calculate the number of floor boards needed to cover the floor:
- Divide the total width of the floor in inches by the width of one floor board.
- [tex]\( \frac{180 \text{ inches}}{2.25 \text{ inches/board}} = 80 \text{ boards} \)[/tex]
Therefore, the number of floor boards required is:
C. 80
