An old medical textbook states that the mean sodium level for healthy adults is 138 mEq per liter of blood. A medical researcher believes that, because of modern dietary habits, the mean sodium level for healthy adults, u, now differs from that given in the textbook. A random sample of 90 healthy adults is evaluated. The mean sodium level for the sample is 140 mEq per liter of blood. It is known that the population standard deviation of adult sodium levels is 11 mEq. Can we conclude, at the 0.05 level of significance, that the population mean adult sodium level differs from that given in the textbook? Perform a two-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places, and round your responses as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis Ho and the alternative hypothesis H,. H P Ho : 0 X S H , : 0 0 (b) Determine the type of test statistic to use. (Choose one) 0=0 030 020 (c) Find the value of the test statistic. (Round to three or more decimal places.) 070 00