Suppose That a Device Advertised to Increase a Car's Gas

Multiple Choice

Suppose that a device advertised to increase a car's gas mileage really does not work. We test it on a small fleet of cars (with H0: not effective) , and our data results in a P-value of 0.004. What Probably happens as a result of our experiment?

A) We fail to reject H0, committing a Type II error.
B) We correctly reject H0.
C) We reject H0, making a Type I error.
D) We correctly fail to reject H0.
E) We reject H0, making a Type II error.