Confidence Intervals and Averages
1. In a certain town, there are 25,000 families. Suppose Census data for the town
shows the true average income is $61,700 and the SD is $50,000. Estimate the
probability that a simple random sample of size 1000 has a sam
Assignment 1 Solutions
3. The parents who refused to allow their children to participate in the experiment
on the premise that the child would be exposed to a higher risk of polio were
incorrect. In the Salk trial, parents who consented were, on the whole
Assignment 5 Solutions
4. (a) The corresponding z-values for 400 and 700 are (400-550)/100=-1.5 and
(700-550)/100=1.5 respectively. To use the normal approximation, we find the area
under the normal curve between -1.5 and 1.5. From the table, we see that
Assignment 7 Solutions
2. (a) We use the regression line to estimate mean values of the dependent variable
for given values of the independent variable. In this case, the regression line is
y-100 = 0.8(x-100) where y represents score at age 35 and x repre
Assignment 13 Solutions
2. (a) The sample is like 500 draws from a 0-1 box of 25,000 tickets. The number
of 1s in the sample is the number of households with internet access. The frac tion
of 1s in the box is unknown, but is estimated by the sample fracti
Assignment 8 Solutions
Ch. 11
3. (a) We use a regression where x is the height at age 6 and y is the height at age
18. The RMS error is
inches.
(b) We switch the meaning of the variables x and y. The RMS error is now
inches.
4. (a) Recall that about 2/3 o
Assignment 9 Solutions
2. The first option is better because there are more ways to win. Getting a king on
the first card and a queen on the second wins $1 under both options, but getting a
king on the first card and, say, and ace on the second card only
ANOVA
Analysis of Variance:
Why do these Sample Means differ as much as they do (Variance)?
Standard Error of the Mean (variance of means) depends upon
Population Variance (/n)
Why do subjects differ as much as they do from one another?
Many Random causes
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Tables
Table A
Standard Normal Probabilities
Table B
Random Digits
Table C t Distribution Critical Values
Table D Chi-square Distribution Critical Values
Table E
Critical Values of the Correla
Assignment 6 Solutions
Ch. 8
1. In graph (a), the means are too low. In graph (b), the SDs are too small. In
graph (c) the SDs are too big and the correlation is too strong. The answer is
(d).
5. (i) 0.60 a moderately strong positive correlation
(ii) 0.30
Significance Testing Practice Answers
First, decide which test of significance is appropriate for each problem. Then go back and answer
each question.
1. In order to test the breaking ability of two types of cars, a simple random of 64 cars of
each type w
Assignment 5 Solutions
4. (a) The corresponding z-values for 400 and 700 are (400-550)/100=-1.5 and
(700-550)/100=1.5 respectively. To use the normal approximation, we find the area
under the normal curve between -1.5 and 1.5. From the table, we see that
Assignment 7 Solutions
2. (a) We use the regression line to estimate mean values of the dependent variable
for given values of the independent variable. In this case, the regression line is
y-100 = 0.8(x-100) where y represents score at age 35 and x repre
Assignment 8 Solutions
Ch. 11
3. (a) We use a regression where x is the height at age 6 and y is the height at age
18. The RMS error is
inches.
(b) We switch the meaning of the variables x and y. The RMS error is now
inches.
4. (a) Recall that about 2/3 o
Assignment 9 Solutions
2. The first option is better because there are more ways to win. Getting a king on
the first card and a queen on the second wins $1 under both options, but getting a
king on the first card and, say, and ace on the second card only
Assignment 13 Solutions
2. (a) The sample is like 500 draws from a 0-1 box of 25,000 tickets. The number
of 1s in the sample is the number of households with internet access. The frac tion
of 1s in the box is unknown, but is estimated by the sample fracti
Math 109 Fall 2011 Test 2 Review
(1) A study of 1,078 families produced the following statistics. Assume the scatter plot is homoscedastic.
average height of father = 68 inches SD = 2.7 inches
average height of son = 69 inches SD = 3.1 inches
correlation
1. A fair six-sided die is rolled 50 times. Estimate the probability of getting
exactly 12 sixes.
2. Suppose 33% of a certain population have O+ blood type. If a random
sample of 900 donors attend a blood drive, what is the probability that the
percent of