# Statistics

posted by Mary

From random sample of 200 college students, 40 students indicated that they smoke cigarettes. Use the information from the sample to calculate a 95% confidence interval for the population proportion of college students that smoke cigarettes (round to nearest hundredth).

A. (0.14, 0.26)
B. (38, 42)
C. (0.17, 0.23)
D. (0.16, 0.24)

1. MathGuru

Formula:

CI95 = p ± (1.96)[√(pq/n)]
...where p = x/n, q = 1 - p, and n = sample size.
Note: ± 1.96 represents 95% confidence interval using a z-table.

For p in your problem: 40/200 = 0.2
For q: 1 - p = 1 - 0.2 = 0.8
n = 200

I let you take it from here to calculate the interval and determine your answer from the selections given.

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