1.A bank randomly selected 247 checking account customers and found that 107 of them also had savings accounts at this same bank. Construct a 90% confidence interval for the true proportion of checking account customers who also have savings accounts.
lower limit:
upper limit:
2.Lung cancer is the leading cause of cancer deaths in both women and men in the United States, Canada, and China. In several other countries, lung cancer is the number one cause of cancer deaths in men and the second of third cause among women. Only about 14% of all people who develop lung cancer survive for 5 years. Suppose you wanted to see if this survival rate were still true. How large a sample would you need to take to estimate the true proportion surviving for 5 years after diagnosis to within 0.4% with 95% confidence?
3. Find the following.
(a) t(13, 0.005)
(b) t(27, 0.05)
(c) t(50, 0.005)
(d) t(12, 0.025)