A shop sells two brands of cola, both of which are sold in multipacks. A multipack of brand A cola costs two pounds 19 and contains eight cans, which are 500 millilitres each. A multipack of brand B cola costs one pound 86 and contains six cans, which are 330 millilitres each. Which brand is the better value? You must show your working.
What does the question mean by better value? It means the lowest cost per unit. And so we need to consider how much cola each multipack is selling us. To do that, we could calculate the price per millilitre. We already know how many millilitres each can is. However, since we’re buying so many cans, we’re better off calculating the price per litre.
Our first step is to then find out how much cola in litres do we get when we buy brand A. Eight cans times 500 millilitres each tells us that brand A gives us 4000 millilitres of cola. We know that 1000 millilitres equals one litre. If 1000 millilitres equals one litre, 4000 millilitres equals four litres. We divide 4000 by 1000, and we get four. For brand A, you pay two pound 90 and you get four litres of cola.
We follow the same procedure for brand B. There are six cans. And each of them contain 330 millilitres of cola. When we multiply six times 330, we get 1980. To convert 1980 millilitres to litres, we’ll need to divide by 1000. And that means we’ll move our digits three places to the right, which would give us 1.98 litres. You could also enter 1980 divided by 1000 into the calculator. Either way, you find that brand B is 1.98 litres of cola for one pound 86.
To calculate the price per litre, we need to divide. We’ll take the cost of the multipack and divide that by the number of litres you get in that multipack. For brand A, 2.90 per, divided, by four litres. Using our calculator to do this division, we get the result 0.725. Since we’re considering cost, money, we need to round to two decimal places. 0.725 rounds to 0.73. For brand A, you pay 73 pence per litre of cola.
Now for brand B, we’ll take one pound 86 and divide by 1.98 litres. When we do this division in our calculator, we get 0.93 repeating. If we write that out, it could look like this. And again, we’ll need to round to two decimal places. 0.93 repeating rounds to 0.94. For brand B cola, we’re paying 94 pence per litre.
Remember that our question is which brand is the better value. So we need to do a comparison of brand A and brand B. 0.73 is less than 0.94. Brand A cost less per litre than brand B. Therefore, brand A is the better value.