Question

A number of minor automobile accidents occur at various high-risk intersections despite traffic lights. The traffic department claims that a modification in the type of light will reduce these accidents. The traffic commissioners have agreed to a proposed experiment. Eight intersections were chosen at random, and the lights at those intersections were modified. The numbers of minor accidents during a six-month period before and after the modifications were as follows:

	Number of Accidents
	A	B	C	D	E	F	G	H
Before modification	11	4	9	9	12	12	8	4
After modification	5	5	3	4	7	4	3	8

At the 0.05 significance level, is it reasonable to conclude that the modification reduced the number of traffic accidents?

a. State the decision rule. (Negative answer should be indicated by a minus sign. Round the final answer to 3 decimal places.)

Reject H₀ if t < _____

=

b. Compute the value of the test statistic. (Negative answer should be indicated by a minus sign. Round the final answer to 3 decimal places.).

The test statistic is=

d. What is the p-value? (Round the final answer to 4 decimal places.)

p=

Answer 1

a)

Reject H₀ if t < -1.895

b) The test statistic is= -2.611

d) p value =0.0174