For every 100 additional people that board a spaceship, its speed is halved. If the speed of the spaceship with 200 people on board is 500km per hour, what is its speed in km/hr when there are 400 people on board?
Reason slowly and give your answer.
125
For every addition of 100 people added the speed is halved so for the first 100 people added its speed is 1 / 2 * 500 km / hr = 250 km / hr.

For another addition of 100 people its speed is also halved, 1 / 2 * 250 km / hr = 125 km / hr.

So for the total of 200 additional people, its speed is 125 km / hr.

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The answer: 125