Question

A jeweler designs necklaces that are perfectly round open- circles each with a radius of 8.4mm. (1m= 1000mm) What is the largest number of open- circle necklaces that can be made from a wheel of spooled gold that is 42m long?

Answer 1

795

Explanation:

First, we find the circumference of 1 ring.

c = 2πr

c = 2 × 3.14159 × 8.4 mm

c = 52.7787 mm

The circumference of 1 ring is the length of spooled gold used for 1 ring.

The spool has a total length of 42 m.

42 m × 1000 mm / 1 m = 42,000 mm

The spool has a total length of 42,000 mm.

Now we divide the length of the spool by the length of 1 ring.

42,000 mm / 52.7787 mm = 795.78

He can make 795 rings.