Proportionality and it's calculation

Question 1

What is direct proportionality?

Answer 1

A relationship where two quantities increase or decrease together at a constant ratio. If one doubles, the other doubles

Question 2

What is inverse proportionality?

Answer 2

A relationship where as one quantity increases, the other decreases, and vice-versa. Their product is constant.

Question 3

Give an example of direct proportionality.

Answer 3

The number of hours you work and the amount you earn (assuming a constant hourly wage).

Question 4

Give an example of inverse proportionality.

Answer 4

The number of workers on a job and the time it takes to complete the job (assuming all workers work at the same rate).

Question 5

What is the “rule of three” used for in percentage calculations?

Answer 5

A method used to solve problems involving proportions, particularly useful for finding a percentage of a number or finding what percentage one number is of another.

Question 6

• How do you calculate a percentage of a number using the
  “rule of three”?

Answer 6

• Set up a proportion:
  percentage = part
  and solve for the
  100
  whole
  unknown.