The spacecraft Gibraltar is a mountain-sized intergalactic vehicle for transporting equipment, building materials, and families to establish colonies on far-away planets.  At full capacity, the vehicle can carry 300 family units with four people per family.  The space flight is expected to take years, and it is expected that the size of families will grow during the space voyage.  Therefore, when the spacecraft leaves the earth, it will carry 100 people less than one-third of the ship's capacity.  How many people will be on the ship to start the journey?
The full capacity of the ship is 300 * 4 = <<300*4=1200>>1200 people.
One-third of capacity is 1200/3 = <<1200/3=400>>400 people.
100 less than one-third capacity is 400 - 100 = 300 people.
#### 300