From Chapter 9
The correct answer is (d).
μ (^) X = 2(0.3) + 3(0.2) + 4(0.4) + 5(0.1) = 3.3.
From Chapter 12
The correct answer is (a). The psychologist’s belief implies that, if she’s correct, μ 1 > μ 2 . Hence,
the proper alternative is H (^) A : μ 1 – μ 2 > 0.
From Chapter 6
The correct answer is (c).
Because she had to be in the top 15%, she had to be higher than the 85th percentile, so she was
invited back.
From Chapter 14
The correct answer is (b). I is true. Another common standard is that there can be no empty cells, and
at least 80% of the expected counts are greater than 5. II is not correct because you can have 1 degree
of freedom (for example, a 2 × 2 table). III is correct because df = (4 – 1) (2 – 1) = 3.
- From Chapter 7
The correct answer is (e). An influential point is a point whose removal will have a marked effect
on a statistical calculation. Because the slope changes from –0.54 to –1.04, it is an influential point. - From Chapter 12
The correct answer is (d). df = 14 – 1 = 13. For a one-sided test and 13 degrees of freedom, 0.075
lies between tail probability values of 0.05 and 0.10. These correspond, for a one-sided test, to t
values of 1.771 and 1.350. (If you have a TI-84 with the invT function, t = invT(1 -0.075,13) =
1.5299. ) - From Chapter 8
The correct answer is (e). Numbers of concern are 1, 2, 3, 4, 5, 6. We ignore the rest. We also ignore
repeats. Reading from the left, the first three numbers we encounter for our subjects are 1, 3, and 5.
They are in the treatment group, so numbers 2, 4, and 6 are in the control group. That’s Betty, Doreen,
and Florence. You might be concerned that the three women were selected and that, somehow, that
makes the drawing nonrandom. However, drawing their three numbers had exactly the same
probability of occurrence as any other group of three numbers from the six. - From Chapter 11
The correct answer is (a). If a significance test at level a rejects a null hypothesis (H 0 : μ = μ 0 )
against a two-sided alternative, then μ 0 will not be contained in a C = 1 – α level confidence interval
constructed using the same value of . Thus, α = 1 – C . - From Chapter 10
The correct answer is (c). The statement in (c) describes the random variable for a geometric setting.
In a binomial setting, the random variable of interest is the number count of successes in the fixed
number of trials.