OpenIntro Chp 3 Exercises

Exercise 2.25

a

i

False, The percentages of people with cardiovascular problems should be compared and not counts.

ii

True

iii

False, Association does not imply causation.

iv

True

b

(7979/227571)

[1] 0.0351

0.0351 is the ratio of people who have cardiovascular disease.

c

67593*(7979/227571)

[1] 2370

d

i

H0-The treatment is independent.HA-The treatment is not independent.

ii

A higher number of patients with heart problems than expected by the graphs.

iii

The variables are not independent.

Exercise 2.27

a

Decreased

b

(24*74+1*64)/(24+1)

[1] 73.6

c

Increased

Exercise 2.31

a

False

b

False

c

True

Exercise 2.34

a

Right Schewed

b

People were faster in the 1990s.

c

Men are faster than women.

d

Finishing times under 2.4 in the 1970s.

Exercise 3.39

Row a

Invalid

Row b

Valid

Row c

Invalid

Row d

Invalid

Row e

Valid

Row f

Invalid

Exercise 3.40

a

459/20000

[1] 0.023

b

4657/20000

[1] 0.233

Exercise 3.41

0.8247

Exercise 3.43

a

e = $3.90, sd = $0.34

b

e = $27.30 sd = $0.89

Exercise 3.47

a^2/n