Use confidence interval formulas for proportions.
CI95 = p + or - (1.96)(√pq/n)
...where √ = square root, p = x/n, q = 1 - p, and n = sample size.
CI90 = p + or - (1.645)(√pq/n)
Hint: x = 396, n = 621
Convert all fractions to decimals to work the formulas.
I hope this will help get you started.
In a survey of 621 males ages 18-64 , 396 say they have gone to the dentist in the past year.
Construct 90% and 95% confidence intervals for the proportion. Interpret the results and compare the widths of the confidence intervals.
Please show step by step. Thank you!
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