a couple of word problems

Quote:

Originally Posted by Patience

A circular coffee table has a diameter of 5 ft. What will it cost to have the
top refinished if the company charges $3 per square foot the refinishing?

The area of the table top is $\pi r^2$ , and here $r=2.5 \mbox(ft)$ (half the diameter), so the area is $\pi \times 2.5^2 \approx 19.6 \mbox{sq ft}$ . So the cost is $\$ 3 \times 19.6=\$58.80$

Quote:

The distant from Philadelphia to Sea Isle City is 100 mi. A car was driven distance using tires with a radius of 14 in. How many revolutions of each tired occurred on the trip?

1 mile is 5280 feet, so 100 miles is 528000 feet.

The circumference of the tires is $2\,\pi\,r$ , so in this case the circumference is ~87.96 inches or ~7.33 feet. So in moving 7.33 feet the tire rotates once.

So in travelling 100 miles each tire will revolve 528000/7.33~72033 times.

RonL