Exhibit 13-12 In a Laboratory Experiment, Data Were Gathered on the Life

question 21

Multiple Choice

Exhibit 13-12
In a laboratory experiment, data were gathered on the life span (Y in months) of 33 rats, units of daily protein intake (X₁) , and whether or not agent X₂ (a proposed life extending agent) was added to the rats diet (X₂ = 0 if agent X₂ was not added, and X₂ = 1 if agent was added.) From the results of the experiment, the following regression model was developed. Also provided are SSR = 60 and SST = 180.
-Refer to Exhibit 13-12. From the above function, it can be said that the life expectancy of rats that were given agent X₂ is

• A)1.7 months more than those who did not take agent X₂
• B)1.7 months less than those who did not take agent X₂
• C)0.8 months less than those who did not take agent X₂
• D)0.8 months more than those who did not take agent X₂