Hello, ferken!

This is a compound interest problem.In 1930, the bluenose stamp could be bought for 50 cents.

In 1987, the same stamp was sold at an auction for 500 dollars.

What annual rate of interest corresponds to an investment of 50 cents in 1930

which grew to 500 dollars in 1987

Formula: . . where: .

We have: .

The formula becomes: .

. .

Therefore: .