Exercise 23 Page 210

Practice makes perfect

a A line of best fit has been determined for the given set of data.

y=0.50x-23.5 We are asked to approximate the height of a student whose shoe size is 9. To do this we will substitute 9 for y in the equation and solve for x.

y=0.50x-23.5

Substitute

y= 9

9=0.50x-23.5

▼

Solve for x

AddEqn

LHS+23.5=RHS+23.5

32.5=0.50x

DivEqn

.LHS /0.5.=.RHS /0.5.

65=x

RearrangeEqn

Rearrange equation

x=65

A student whose shoe size is 9 is approximately 65 inches tall.

b To predict the shoe size of a student whose height is 60 inches, we will use the equation of the line of best fit.

y=0.50x-23.5 Let's substitute 60 for x into the model and solve it for y.

y=0.50x-23.5

Substitute

x= 60

y=0.50( 60)-23.5

Multiply

y=30-23.5

SubTerm

Subtract term

y=6.5

Therefore, the shoe size is 6.5.

Subchapter links

1 Writing Equations in Slope-Intercept Form p.208

2 Writing Equations in Point-Slope Form p.208

3 Writing Equations of Parallel and Perpendicular Lines p.209

4 Scatter Plots and Lines of Fit p.209

5 Analyzing Lines of Fit p.210

6 Arithmetic Sequences p.210

Exercise 23 Page 210

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