For the purposes of this Division, the monthly average volumetric vapour pressure, expressed in kPa, of petrol that is not ethanol-blended petrol produced by a regulated petrol producer is determined in accordance with the following formula—
where—
n is the total number of batches of petrol that are not ethanol-blended petrol produced during the relevant month by the producer; and
B i is the volume, expressed in litres, of a batch of petrol that is not ethanol-blended petrol; and
S i is the vapour pressure, expressed in kPa, of a batch of petrol that is not ethanol-blended petrol; and
G is the total volume, expressed in litres, of petrol that is not ethanol-blended petrol produced in a month by the producer.