STAT 200 Final Exam Answers
True or False. Justify for full credit.
(a) The standard deviation of a data set cannot be negative.
(b) If P(A) = 0.4 , P(B) = 0.5, and A and B are disjoint, then P(A AND B) = 0.2.
(c) The mean is always equal to the median for a normal distribution.
(d) A 95% confidence interval is wider than a 98% confidence interval of the same parameter.
(e) In a two-tailed test, the value of the test statistic is 1.5. If we know the test statistic follows
a Student’s t-distribution with P(T < 1.5) = 0.98, then we fail to reject the null hypothesis
at 0.05 level of significance .
Identify which of these types of sampling is used: cluster, convenience, simple random,
systematic, or stratified. Justify for full credit.
(a) A STAT 200 professor wants to estimate the study hours of his students. He teaches two sections, and plans on randomly selecting 10 students from the first section and 15 students
from the second section.