Auto Batteries. In October 2002, Consumer Reports listed the price (in dollars) and power (in cold cranking amps) of auto batteries. We want to know if more expensive batteries are generally better in terms of starting power. Here are the regression and residual output, where the response variable is Power.

a) How many batteries were tested?

b) Are the conditions for inference satisfied? Explain.

c) Is there evidence of a linear association between the price and cranking power of auto batteries? Test an appropriate hypothesis and state your conclusion.

d) Is the association strong? Explain.

e) What is the equation of the regression line?

f) Create a 90% confidence interval for the slope of the true line.
g) Interpret your interval in this context.

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Dependent variable is: Power R squared = 25.2% s = 116.0 with 33 2 31 degrees of freedom Coefficient SE (Coeff) Variable t-ratio P-value Intercept 384.594 93.55 4.11 0.0003 Price 4.146 1.282 3.23 0.0029 Power (cold cranking amps) Residuals (cold cranking amps) 900 800+ 700 600 500 200 100 -100 \.000 50 75 100 Price ($) 600 GOOD 700 800 Predicted (cold cranking amps)