A GOLDEN CROWN?

The King asks Archimedes if his crown is made from pure gold.
He know that the crown is either pure gold or it may have some silver in it.
Archimedes figures out that the volume of the crown is 125 cm^3 and that its mass is 1.8 kilograms.
He also knows that 1 kilogram of gold has a volume of about 50 cm^3 and 1 kilogram of silver has a volume of about 100 cm^3.

1.  Is the crown pure gold?  Explain how you know.

2.  If the crown is not pure gold, then how much silver is int it?  Show all your work.
October 24
100 PEOPLE

There are approximately seven billion (7 * 10^9) people in the world.

In the 1990s researchers calculated that if there were just 100 people in the world
    -there would be 20 children
    -25 people would not have food and shelter
    -17 people would speak Chinese
    - 8 people would speak English

1.  What fraction of people in the world do not have food and shelter?  How many people in the world do not have food and shelter?

2.  How many more people in the world speak Chinese than speak English?

3.  Approximately 3 * 10^8 people live in the USA.  In the world of 100 people, how many would live in the USA?