Question

A necklace contains twenty-four spherical beads of silver, each having a radius of 0.5cm. The beads are to be coated, and the cost of coating is $10 per cm2. What is the approximate total cost, to the nearest cent, for coating the beads?

Answer 1

$153

Explanation:

To find the total cost, we have to calculate the area of one bead, then all of them:

Area of one bead = pi x r^2 = 3.14 x 0.5^2 = 3.14 x 0.25 = 0.765cm^2

Area of 20 beads = 0.765 x 20 = 15.3cm^2

Now, we are able to calculate the ultimate cost of coating:

If the cost is $10 per cm^2, then we have to find how much it costs to coat 15.3 cm^2.

15.3 x 10 = $153.

Hope this helps