1. PROPORTION Given that y is proportional to x, find the missing values of y x25102050 y18

2. PROPORTION The current, I, in a particular wire is proportional to the voltage, V. If I = 8 amps when V = 5 volts then find (a)The current when the voltage is 8 volts (b) The voltage if the current is 10 amps.

3. PROPORTION There can be other ways in which two variables are directly proportional to each other. Consider the formula for the area of a circle…… A is directly proportional to the SQUARE of the radius. The constant k = 3.14….

4. PROPORTION Other relationships to consider…. y varies directly with the square of x y varies directly with the square root of x

5. EXAMPLE It is known that a is proportional to the square of n. Complete the table… n25820 a8200

6. EXAMPLE 2 If a stone is dropped from the top of a building, the time t, to reach the ground is proportional to the square root of the height h of the building. Given that a stone takes 4.5 secs to fall 100 feet, how long will it take to fall 50 feet? COMMON MISTAKE ! Do not halve the time!!!!! FIND THE CONSTANT OF PROPORTIONALITY FIRST