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 H_{0} 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=
a)
Reject H_{0} if t < -1.895
b) The test statistic is= -2.611
d) p value =0.0174
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