Final answer:
David's unit rate is 3 miles per hour, which is calculated by dividing the distance of the lap (1/3 mile) by the time it takes (1/9 hour).
Step-by-step explanation:
To calculate David's unit rate in miles per hour, we need to divide the distance of one lap around the block by the time it takes to complete that lap. Since one lap is 1/3 mile and it takes David 1/9 hour to drive one lap, the unit rate is found by dividing 1/3 mile by 1/9 hour.
We can calculate this by finding the reciprocal of 1/9 hour and multiplying it by 1/3 mile:
- 1/9 hour → The reciprocal is 9/1 hours or simply 9.
- Multiply 1/3 mile by 9: (1/3) × 9 = 3.
Therefore, David's unit rate is 3 miles per hour. This represents the speed at which David drives around the block.