Question

It is generally believed that nearsightedness affects about 15% of children. A school district gives vision tests to 111 incoming kindergarten children. In our sample of 111 students, we find 13% of the students were nearsighted. Construct a 90% confidence interval for the number of nearsighted kindergarteners we would expect to see based on our sample. Does this support or refute the estimate of 15%? Assume conditions are met (so don't check them)!

Now that you have your interval, we want to test a hypothesis. The school district believes that the estimate of 15% is too high. We will test a hypothesis (with an alpha-level of 0.05) to report to the district, again using our observed value of 13% in a sample of 111. Keep in mind that your conclusion for your test should agree with your confidence interval results. This means that if you fail to reject the null hypothesis, the hypothesized value of 0.15 should fall in the interval. If you reject the null hypothesis, the hypothesized value of 0.15 should fall below the interval. Extra points for checking your work by performing the interval and test in StatCrunch and attaching those results as a picture!

Answer 1