Comparing the unit prices
The unit price is the price of a single measure of a product. It could be a gram, a millilitre or one item (like one apple).
Often a product comes in packets of different sizes and prices. It is useful to compare the unit price in deciding which size of packet to buy.
Example
A breakfast cereal comes in three packet sizes.
Which packet is best value for money?
Answer
Small packet unit cost \(= 205\) pence \(\div 250 = 0.82\) pence per gram
Medium packet unit cost \(= 285 \div 375 = 0.76\) pence per gram
Large packet unit cost \( = 315 \div 500 = 0.63\) pence per gram
The large packet works out as cheapest per gram, so is best value.
Question
Which tin is best value for money?
Small tin unit cost \(= \pounds7.60 \div 1 = \pounds7.60\) per litre
Medium tin unit cost \(= \pounds15.80 \div 2.5 = \pounds6.32\) per litre
Large tin unit cost \(= \pounds26.50 \div 5 = \pounds5.30\) per litre
The large tin works out as cheapest per litre, so is best value.
