Answer:

1.There is a direct proportion between two values when one is a multiple of the other. For example, 1 cm = 10 mm . To convert cm to mm, the multiplier is always 10. Direct proportion is used to calculate the cost of petrol or exchange rates of foreign money.

2.Inverse proportion occurs when one value increases and the other decreases. For example, more workers on a job would reduce the time to complete the task. They are inversely proportional.

3.A partitive proportion, or proportion by parts, describes a whole amount being divided or distributed into two or more unequal parts. Example: The ratio of boys to girls in a class is 3:5. If there are 48 students in the class, how many boys and girls are there?