The accompanying data on and power (W) for a certain laser configuration was read from a graph in the article “Frequency Dependence in RF Discharge Excited Waveguide CO2 Lasers” (IEEE J. of Quantum Electronics, 1984: 509–514).

x | 60 63 77 100 125 157 186 222 y | 16 17 19 21 22 20 15 5 A computer analysis yielded the following information for a quadratic regression model:

, and when .

a. Does the quadratic model appear to be suitable for explaining observed variation in output power by relating it to frequency?

b. Would the simple linear regression model be nearly as satisfactory as the quadratic model?

c. Do you think it would be worth considering a cubic model?

d. Compute a 95% CI for expected power output when frequency is 100.

e. Use a 95% PI to predict the power from a single experimental run when frequency is 100.