When dealing with rates, it basically involves two quantities. Most appropriate word to use between the two related quantities is “per”. One quantity may in the denominator to express the rate of change per quantity. The common type of rate we use in everyday life is rate “per” unit of time. Time will be our main denominator to find a rate of a quantity which is the rate of time per quantity (numerator).

Rules:

Examples

Salary rate

E.g. Rate at which the Coca-Cola company pays his employee.

Electricity rate

E.g. Rate at which PNG Power charges its customer on electricity usage

Power rate

E.g. Rate at which your laptops or Mobile phones are using the battery

Quiz:

The hourly rate for an employee works for coca cola company in Lae is K4.00/h. How much will the employee total salary in a fortnight when he works 8 hours a day and takes a day off every Monday? Ans K416

The rate of a Dell laptop loses its battery power 1% per 4mins. If the laptop is fully charged to 100%.

how long will it take for the laptop to reach 70%? Ans:  120mins

how long will it take for the laptop to reach 30%? Ans: 280mins