A regression was run to determine if there is a relationship between the happiness index (y) and life expectancy in years of a given country (x).

The results of the regression were:

y

y^=a+bx

a=0.318

b=0.082

(a) Write the equation of the Least Squares Regression line of the form

y

y^=+x

(b) Which is a possible value for the correlation coefficient,r

r

?

• -0.639
• 0.639
• 1.678
• -1.678

(c) If a country increases its life expectancy, the happiness index will

• increase
• decrease

(d) If the life expectancy is increased by 4.5 years in a certain country, how much will the happiness index change? Round to two decimal places.

(e) Use the regression line to predict the happiness index of a country with a life expectancy of 78 years. Round to two decimal places.