Data was collected on age in years and blood pressure in mil

Data was collected on age (in years) and blood pressure (in millimeters of mercury) from a sample of people living in a particular country. A scatterplot of the data was produced.

The method of least squares was used to fit a straight line model to this data. The equation of the least squares fit line is

y = 98.7 + 0.971x

a) choose more meaningful labels for the explanatory and dependant variables, and hence write down an equation that may be used to model the relationship between a person\'s age and their blood pressure.

b) Use this equation to predict the blood pressure for a person whose age is 45 years.

c) Person A is 5 years older than person B. According to the model, what is the prediced difference between the blood pressures of person A and person B?

Solution

a. Let write presure (P) for y and and age in year ( A) for x .Thus model will become

P=98.7 + 0.971 A

.971A=P- 98.7

A=(P-98.7)/.971 (i)

b. We have age 45 years.

P= 98.7+0.971 x (45)

=142.395 mm

c. Let age of Person B= x years ,so age of Person A=x+5

PB=Blood presure of person B= 98.7+.971x

PA= Blood presure of person A=98.7+.971(x+5)

difference in Blood presure= PA-PB

=98.7+.971(x+5)-98.7-.971x

=.971 x 5

=4.855 mm