Be sure to state the Ho and H1 The use of cellular phones in automobiles has inc
ID: 3260719 • Letter: B
Question
Be sure to state the Ho and H1
The use of cellular phones in automobiles has increased dramatically in the last few years. Of concern to traffic experts, as well as manufacturers of cellular phones, is the effect on accident rates. Is someone who is using a cellular phone more likely to be involved in a traffic accident? What is your conclusion from the sample information? Use the .05 significance level.
Had accident No accidents
Used cell 25 300
Did not use cell 50 400
Explanation / Answer
Had accident No accidents ........ total
Used cell 25 300 325
Did not use cell 50 400 450
total 75 700 775
Ho: the use of cellular phone is independent of having traffic accident
Ha: the use of cellular phone is not independent ofhaving traffic accident
crititcal value = X^2(0.05 , 1) = 3.8415
Reject Ho if X^2 >3.8415
expected value of
use cell and had accident = 325 * 75/775 = 31.45
use cell phone and didnt have accident = 325 * 700/775 = 293.55
does not use cell phone and had accident = 450 * 75/775 = 43.55
does not use cell phone and didnt have accident = 450 * 700/775 = 406.45
test static = (25 - 31.45)^2/31.45 + (300-293.55)^2/293.55 + (50 -43.55)^2/43.55 + (400 - 406.45)^2/406.45
= 2.522
hence we did not reject Ho
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