Calculations can be carried out using percentages of shapes and quantities. We can calculate percentage increase and decrease, as well as express a quantity as a percentage of another quantity.
Part of Application of MathsNumeracy skills
If money is not left in a bank account for a whole year then only a fraction of the interest gets paid.
Find the interest that Damon earns on \(\pounds40\) if he keeps it in the bank, paying \(8.5\%\) interest p.a., for 6 months.
Interest for one year \(= 8.5\%\,of\,\pounds40\)
\(= \frac{{8.5}}{{100}} \times 40\)
\(= 0.085 \times 40\)
\(= \pounds3.40\)
You now know the interest for one year, so to find the interest per month, divide by 12 then multiply by the number of months.
Interest for \(1\,month = \pounds3.40 \div 12 = \pounds0.28333\)...
Interest for 6 months \(= \pounds0.28333... \times 6 = \pounds1.70\)
New balance = \(\pounds40 + \pounds1.70 = \pounds41.70\)
Damon will earn \(\pounds1.70\) in interest.