An ecologist randomly samples 10 plants of a specific species and measures their heights. He finds that this sample has a mean of 12 cm and a standard deviation of 4 cm. If we assume that the height measurements are normally distributed, find a 95% confidence interval for the mean height of all plants of this species. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.) What is the lower limit of the confidence interval? What is the upper limit of the confidence interval?
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From the t-table, the critical value for a 95% confidence interval with 9 degrees of freedom is 2.262. Show more…
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