15.1 The correlation is r = 0.994, and the least-squares linear regression equation is
y = 3.66 + 1.1969 x , where y = humerus length and x = femur length. The scatterplot with the
regression line below shows a strong, positive, linear rela
13.1 (a) Counts will be obtained from the samples so this is a problem about comparing
proportions. (b) This is an observational study comparing random samples selected from two
13.2 (a) Scores will be ob
12.1 (a) 2.015. (b) 2.518.
12.2 (a) 2.145. (b) 0.688.
12.3 (a) 14. (b) 1.82 is between 1.761 ( p = 0.05) and 2.145 ( p = 0.025) . (c) The P-value is
between 0.025 and 0.05. (In fact, the P-value is 0.0451.) (d) t = 1.82 is signif
11.1 (a) = the mean score for all older students at this college. (b) If = 115 , the sampling
distribution of x in Normal with mean 115 and standard deviation 30 25 = 6 or N(115, 6).
See the sketch below (on the left). (c) Assuming H 0 is t
5.1 The population is (all) local businesses. The sample is the 73 businesses that return the
questionnaire, or the 150 businesses selected. The nonresponse rate is 51.3% = 77/150.
Note: The definition of sample makes it somewhat unclear whe
10.1 (a) The sampling distribution of x is approximately normal with mean x = 280 and
2.0702 . (b) The mean is 280. One standard deviation from
standard deviation x =
the mean: 277.9 and 282.1; two standard deviations from the me
6.1 Answers will vary but examples are: (a) Flip the coin twice. Let HH represent a failure, and
let the other three outcomes, HT, TH, TT, represent a success. (b) Let 1, 2, and 3 represent a
success, and let 4 represent a failure.
9.1 (a) =2.5003 is a parameter (related to the population of all the ball bearings in the
container and x =2.5009 is a statistic (related to the sample of 100 ball bearings). (b) p =7.2%
is a statistic (related to the sample of registered vo
3.1 (a) The amount of time a student spends studying is the explanatory variable and the grade
on the exam is the response variable. (b) Height is the explanatory variable and weight is the
response variable. (c) Inches of rain is t
8.1 Not binomial: There is not fixed number of trials n (i.e., there is no definite upper limit on
the number of defects) and the different types of defects have different probabilities.
8.2 Yes: 1) Success means person says Yes an
7.1 (a) P(less than 3) = P(1 or 2) = 2/6 = 1/3. (b)(c) Answers will vary.
7.2 (a) The possible arrangements are: BBB, BBG, BGB, GBB, GGB, GBG, BGG, GGG. Each
arrangement has probability 1/8. (b) Three of the eight arrangements have