In: Statistics and Probability
An insurance company would like to test the hypothesis that a difference exists in the proportion of students in 12th grade who text while driving when compared to the proportion of
11th-grade drivers who text. A random sample of 160 12th grade students found that 84 texted while driving. A random sample of 175 11th grade students found that 84 texted while driving. A random sample of 175 12th grade drivers and Population 2 is defined as 11th-grade drivers. What is the 95% confidence interval for the difference in population proportions?
A.
(−0.119,0.369)
B.
(0.019, 0.231)
C.
(−0.037,0.287)
D.
(0.103, 0.147)
let p1 be the proportion denoting the proportion of 12th grade students and p2 be the proportion denoting 11th grade students.
According to data given in the question
p1 = 84/160 = 0.525 and n1 = 160 (sample size)
p2 = 70/175 = 0.40, n2 = 175 (sample size)
we have to find 95% confidence interval for proportion difference
z critical value for 95% confidence interval is 1.96 (using z distribution table)
Formula for the confidence interval is given as
setting the given values, we get
this gives us
Therefore, option B is correct answer for the required 95% confidence interval