15. Researchers claim that the data they collected provide sufficient evidence to indicate that the mean serum uric acid levels for individuals with Down’s syndrome is greater than that for normal individuals. The data consist of serum uric acid readings on 12 individuals with Down's syndrome and 15 normal individual. The sample results are:
Down’s syndrome Normal
Sample Size n1 = 12 n2 = 15
Sample Mean x̄1 = 4.5 x̄2 = 3.4
Sample Variance s1² = 1.0 s2² = 1.5
Assume that σ1² = σ2². Perform an appropriate test to determine whether the data present sufficient evidence to support the researcher's claim. Compute the test statistic. (Round off your answer to two decimal places.)
(a) 2.79
(b) 2.51
(c) 1.71
(d) 2.16
(e) None of these
16. Refer to Question 15, what is the p-value? (Round off your answer to four decimal places.)
(a) 0.7387
(b) 0.2613
(c) 0.9905
(d) 0.0095
(e) None of these
17. Refer to Question 15, construct a 95% confidence interval for the difference μ1 – μ2 of population means. (Round off your answer to four decimal places.)
(a) [0.2184, 2.2816]
(b) [0.1867, 2.3163]
(c) [0.1974, 2.0026]
(d) [0.1946, 2.3054]
(e) None of these