The article Readibility of liquid crystal displays a respons

The article \"Readibility of liquid crystal displays: a response surface\" used a multiple regression model with four independent variables, where

y = error percentage for subjects reading a four digit liquid crystal display

x₁ = level of blacklight (from 0 to 122 cd/m)

x₂ = character substence (from .025 degrees to 1.34 degrees)

x₃ = viewing angle (from 0 degrees to 60 degrees)

x₄ = level of ambient light (from 20 to 1500 lx)

The model equation suggested in the article is

y = 1.52 + .02x₁ - 1.40x₂ + .02x₃ - .0006x₄ + e

Assume that this is the correct equation. What is the mean value of y when x₁ = 10, x₂ = .5 , x₃ = 50 , x₄ = 100?

Solution