Using Formulas to Solve Problems LG: I can solve real-world problems by substituting values into formulas and solving.

INVESTIGATION These formulas give the height, h, of an adult. They rely on the lengths of the radius bone, r, and the femur bone, f. (Note: All measurements are in centimeters) A) predict the height of a female whose femur is 40.6 cm long MALE FEMALE Using the radius bone h = 3.65 r + 80.41 h = 3.88 r + 73.50 Using the femur bone h = 2.24 f + 69.09 h = 2.32 f + 61.41

INVESTIGATION These formulas give the height, h, of an adult. They rely on the lengths of the radius bone, r, and the femur bone, f. B) predict the height of a male whose radius is 28.1 cm long. MALE FEMALE Using the radius bone h = 3.65 r + 80.41 h = 3.88 r + 73.50 Using the femur bone h = 2.24 f + 69.09 h = 2.32 f + 61.41

INVESTIGATION These formulas give the height, h, of an adult. They rely on the lengths of the radius bone, r, and the femur bone, f. C) Complete the chart D) Which formula gave you the more accurate prediction? MALE FEMALE Using the radius bone h = 3.65 r + 80.41 h = 3.88 r + 73.50 Using the femur bone h = 2.24 f + 69.09 h = 2.32 f + 61.41 Length of yours Calculation of your height Actual height Radius Femur

What is a formula? It’s a mathematical equation that relates two or more variables, which each represent real-world quantities. Can you think of any examples from work or school?

Example 1 – Substituting into a formula Pediatric nurses use Young’s formula, to calculate a child’s dose of medicine. C is the child’s dose in milligrams A is the adult’s dose in milligrams g is the child’s age in years. If the adult dose of a medication is 600 mg, what would be a 3-year-old’s dose?

Example 2 – Choosing Formulas and Converting Measures A landscaper uses a bucket with radius 18 cm and height 18 cm to pour soil into a rectangular planter that measures 1 m by 40 cm by 20 cm. How many buckets of soil are needed to fill the planter? Work in partners or a group of 3 to figure out the answer to this.

Investigation: How much do I need to eat? What is a BMR? Used to determine the amount of energy required by the body at rest. This value can then be adjusted depending on activity level Use the Harris-Benedict Equation to calculate your BMR You will need: Age in years Weight in kg (pounds x 2.2) Height in cm (measuring tapes available)

Example 3