JAMB 1985 · UME · Q2

A sum of money was invested at $8\%$ per annum simple interest. If after 4 years the money amounts to ₦330.00, find the amount originally invested.

Worked solution (try it first)

Simple interest for 4 years at $8\%$ is $4 \times 8\% = 32\%$ of the principal $P$ .
The amount is principal plus interest, so $1.32P = 330$ .
Divide both sides by 1.32: $P = 250$ .
The amount invested was ₦250.00, option E.