## Brief Solutions to Practice Test 2

Problem 1
(b) Q1 = 55, median = 60, Q3 = 69
(c) 64.4 +/- (2.064)(16.1)/sqrt(25), or 64.4 +/- 6.7.
(d) There are two outliers (\$110, \$109), but the sample is large enough that the resultant skewness should not be too bad.
(e) If the shoes were not randomly sampled from some well-defined population, the confidence intervals may be unreliable.

Problem 2
(a) z = -1.32, area = 0.0934
(b) 65 - 1.645(19) = 33.7
(c) z = -2.63, area = 0.0043

Problem 3
(b) 39!/(18!21!) (.524)^18 (.476)^21 = 0.0939.
(c) (.524)^9 = 0.0030.
(d) z = (59.5-52.4)/sqrt( (100)(.524)(.476) ) = 1.42, area = 0.0778.
Problem 4
(a) mean = 244.5, sd = 21.7; 99% CI: 244.5 +/- (3.499)(21.7)/sqrt(8) or 244.5 +/- 26.8
(b) t = 2.54; .01 < one sided p-value < .02

Problem 5
False, it means that the data observed is fairly typical if the null hypothesis is true.

Problem 6
False, it means that tall men tend to marry tall women and short men tend to marry short women.

Problem 7
True.

Problem 8
True.

Problem 9
False, association is not causation.

Problem 10
True.

Problem 11
True.

Problem 12
False, it is 20!/(10!10!).