Science:Math Exam Resources/Courses/MATH221/December 2007/Question 09 (c)/Statement

On a remote planet, moisture is present in clouds, on the continents, and in the seas.

• Each year 80% of the cloud moisture falls onto the land and 10% falls into the seas.
• Each year 15% of the land moisture evaporates directly into the clouds and 65% runs into the seas.
• Each year 70% of the sea moisture evaporates into the clouds.

Assume we know also that the total amount of water or moisture on the planet is 86 trillion litres.

Suppose the planets moisture distribution is in equilibrium. What is the annual precipitation (volume of water falling onto land from the clouds)?