Dirt bikes 2014, part  2.

In Exercise 41, we saw data on off-road motorcycles and examined scatterplots. Review those scatterplots. Here’s a regression of MSRP on both Displacement and Bore. Both of the predictors are measures of the size of the engine. The displacement is the total volume of air and fuel mixture that an engine can draw in during one cycle. The bore is the diameter of the cylinders.

Response variable is: MSRP R squared = 72.2% R squared (adjusted) = 71.7%

s = 1299 with 114 - 3 = 111 degrees of freedom Variable Coefficient SE(Coeff) t-ratio P-value Intercept -323.299 1197 -0.270 0.7875 Displacement 4.38220 4.108 1.07 0.2884 Bore 82.9084 30.54 2.71 0.0077

a) State and test the standard null hypothesis for the coefficient of Displacement.

b) Both of these predictors seem to be linearly related to MSRP. Explain what your result in part a means.