In testing eight value notebook computers, PC World reported various physical and performance measures of each. Data included overall rating, street price, PC WorldBench 4 performance score, and battery life, with the results shown here.
a. From these data, obtain the multiple regression equation estimating overall rating on the basis of the other three variables; then determine and interpret the approximate 95% confidence interval for the mean overall rating of notebook computers having a $1000 street price, a performance score of 100, and a 2.50-hour battery life.
b. Determine the 95% prediction interval for the overall rating of an individual notebook computer with a $1000 street price, a performance score of 100, and a 2.50-hour battery life.