QUESTION

A Botanist studying palms is comparing stem diameters of Areca palms and Phoenix palms. She measures 19 randomly selected Areca palms and finds a lot of variation (s=0.16m), whereas there is less variation among the Phoenix palms (s=0.06m). She decides to figure out the confidence interval for the population standard deviation of the Areca palms.

a. Which distribution table should she use for her calculations?

b. What is the equation that she will need to use?

c. Use the equation and the table to calculate the confidence interval. Show all steps.

Keep at least 4 decimal places in your answer.

d. Express the confidence interval with the values rounded off according to the applicable round off rule

e. Suppose you needed to determine the 99% confidence interval, what would be the values for the left and right-tailed critical values?

f. If you wanted to be 99% confident that the sample standard deviation was within 10% of the true value, what sample size would you use?