Direct Proportionality

The cost, c, of a circular table is directly proportional to the square of the radius, r. A circular table with a radius of 40cm cost £50. What is the cost of a circular table with a radius of 60cm?

H varies directly to the cube of c. When H = 40, c = 2. Find the value of c when H = 5000.

C is directly proportional to the square root of y. When C = 12.8, y = 16. Find C when y = 400.

What is the constant of proportionality?

• $3

• $4

• $2

• $9

y=kx.  What does the k represent?

• constant of proportionality

• multiplier

• scale factor

• all of these are correct

Is this table proportional or non-proportional?

• Proportional

• Non-Proportional

What is the Constant of Proportionality?

• k=46

• k=92

• k=0.2

• not proportional