A study investigated if cell phone use impacted student drivers\' reaction times

Question

A study investigated if cell phone use impacted student drivers' reaction times. There were two groups: 23 students were assigned to the cell phone group while 23 students were assigned to the control group. The experiment measured the response time to traffic lights; for the cell phone group, the mean was 587 with a standard deviation of 89.7 and for the control group, the mean was 534.3 with a standard deviation of 65.1. Construct a 90% confidence interval for the difference in mean response times between the cell phone and control groups.

a. x bar 1-x bar 2=

b.margin of error=

c. lower and upper limit

d. we are ___% confident that the true in difference of population means is between ___ and ___

Explanation / Answer

Ans:

a)Point estimate=587-534.3=52.7

b)pooled standard deviation=sqrt(((23-1)*89.7^2+(23-1)*65.1^2)/(23+23-2))

=78.37

standard error for difference=78.37*sqrt((1/23)+(1/23))=23.11

df=23+23-2=44

critical t value=tinv(0.05,44)=1.680

margin of error=1.680*23.11=38.83

c)lower limit=52.7-38.83=13.87

upper limit=52.7+38.83=91.53

d)we are 90% confident that the true in difference of population means is between 13.87 and 91.53

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