Question

Calcium is essential to tree growth because it promotes the formation of wood and maintains cell walls. In​ 1990, the concentration of calcium in precipitation in a certain area was 0.12 milligrams per liter​ (mg/L). A random sample of 10 precipitation dates in 2007 results in the following data table. Complete parts​ (a) through​ (c) below. LOADING... Click the icon to view the data table. ​(a) State the hypotheses for determining if the mean concentration of calcium precipitation has changed since 1990. Upper H 0​: ▼ sigma p mu ▼ greater than equals less than not equals 0.12 ​mg/L Upper H 1​: ▼ p sigma mu ▼ less than not equals equals greater than 0.12 ​mg/L ​(b) Construct a 90​% confidence interval about the sample mean concentration of calcium precipitation. The lower bound is nothing. The upper bound is nothing. ​(Round to four decimal places as​ needed.) ​(c) Does the sample evidence suggest that calcium concentrations have changed since​ 1990? A. Yes​, because the confidence interval contains 0.12 ​mg/L. B. No​, because the confidence interval contains 0.12 ​mg/L. C. Yes​, because the confidence interval does not contain 0.12 ​mg/L. D. No​, because the confidence interval does not contain 0.12 ​mg/L.

0.066	0.087	0.069	0.237	0.116
0.172	0.116	0.247	0.337	0.107

Answer 1