Watch me work it in the video below…

With buoyancy questions the SIMPLEST approach is to look at the answers and determine the unit of measurement they are looking for. In this question it is KG.

So having determined that we need to convert the litres given in the question to KG, then all our numbers in the same unit of measurment.

Take the 80Litres x 1.03=82.4KG

We have just calculated the total amount of weight that is needed.

The other number in the question is the weight of the diver - 70KG

So 82.4kg - 70KG= 12.4KG Is the amount of weight we need to add to the diver.