Module 1: The International System of Units (SI)
Mastering Concepts
MC 1. Volume of precipitation = area of Vancouver × annual precipitation.
The units you use must be the same.
In metres,
There are 1000 L in 1 m3.
MC 2. The volume of the annual precipitation in Vancouver is 138 000 000 000 L.
So, each person on Earth would receive 
or 19.714 L. This is about 20 L per person.