An article in Wear (1992, Vol. 152, pp. 171-181) presents data on the fretting wear of mild steel and oil viscosity. Representative data follow with x = oil viscosity and y = wear volume (10^(-4) cubic millimeters).
Round your answers to two decimal places (e. g. 98.76).

Engine MPG
Carline Displacement (in^3) (highway)
300C/SRT-8 215 30.8
CARAVAN 2WD 201 32.5
CROSSFIRE ROADSTER 196 35.4
DAKOTA PICKUP 2WD 226 28.1
DAKOTA PICKUP 4WD 226 24.4
DURANGO 2WD 348 24.1
GRAND CHEROKEE 2WD 226 28.5
GRAND CHEROKEE 4WD 348 24.2
LIBERTY/CHEROKEE 2WD 148 32.8
LIBERTY/ CHEROKEE 4WD 226 28
NEON/SRT 4/SX 2.0 122 41.3
PACIFICA 2WD 215 30.0
PACIFICA AWD 215 28.2
PT CRUISER 148 34.1
RAM 1500 PICKUP 2WD 500 18.7
RAM 1500 PICKUP 4WD 348 20.3
SEBRING 4-DR 165 35.1
STRATUS 4-DR 148 37.9
TOWN & COUNTRY 2WD 148 33.8
VIPER CONVERTIBLE 500 25.9
WRANGLER/TJ 4WD 148 26.4

y 240 181 193 155 172 110 113 75 94
x 1.6 9.4 15.5 20.0 22.0 35.5 43.0 40.5 33.0

(a) Construct a scatter plot of the data. Does a simple linear regression model appear to be plausible?
(b) Fit the simple linear regression model using least squares. Find an estimate of σ2.
(c) Predict fretting wear when viscosity x = 30.