2.1

7 a:China

b:approximately 50 million internet users

c:approximately 355 million more internet users in China

d:because China’s population is higher than those of other countries, relative frequency is better choice to be used.

9 a:approximately 70%

b:approximately 55.2 millions

c:inferential because there is no evidence to support Gallup’s claim to be descriptive.

11 a:0.42% of 18-to 34-year-old ,0.61% of 35-to 44-year-old

b:55 +

c:18-to 34-year-old

d:As the older they are, the more likely they are to buy products made in America

13 a:never-0.03, rarely-0.07, sometimes-0.12, most of the time-0.26, always-0.53

b:52.7%

c:9.4%

my_data <- c(125, 324, 552, 1257, 2518 )

groups <- c("never", "rarely", "sometimes", "most of the time", "always")

barplot(my_data, main = "Frequency of How often do you wear seatbelt", names.arg = groups)

my_data <- c(0.03, 0.07, 0.12, 0.26, 0.53 )

groups <- c("never", "rarely", "sometimes", "most of the time", "always")

barplot(my_data, main = "Relative Frequency of How often do you wear seatbelt", names.arg = groups)

pie(my_data, labels = groups, main = "Pie Chart of How often do you wear seatbelt")

g:descriptive statement because it is analysis of a fact.

15 a:more than 1 hour a day-0.37, up to 1 hr a day-0.19, a few times a week-0.13, a few times a month or less-0.08, never-0.24

  b:approx. 23.7%
 
 
 
my_data <- c(377, 192, 132, 81, 243 )

groups <- c("more than 1 hour a day", "up to 1 hour a day", "a few times a week", "a few times a month or less", "never")

barplot(my_data, main = "Frequency of Period of Time Adult Americans using for internet", names.arg = groups)

my_data <- c(0.37, 0.19, 0.13, 0.08, 0.24 )

groups <- c("more than 1 hour a day", "up to 1 hour a day", "a few times a week", "a few times a month or less", "never")

barplot(my_data, main = "Relative Frequency of Period of Time Adult Americans using for Internet", names.arg = groups)

pie(my_data, labels = groups, main = "Pie Chart of Period of Time Adult Americans Using for Internet")

  f:the number of the percentage is not exactly known.

2.2

  1. a:8

b:2

c:15 more times

d:4

e:15%

f:bell-shaped

10 a:4

b: 9

c: about 17%

d:bell-shaped

11 a:200 students

b:10

c:60-69=2, 70-79=3, 80-89=13, 90-99=42, 100-109=58, 110-119=40, 120-129=31, 130-139=8, 140-149=2, 150-159=1

d:100-109

e:150-159

f:5.5%

g:none

12 a:200

b:0-199, 200-399, 400-599, 600-799, 800-999, 1000-1199, 1200-1399, 1400-1599

c:0-199

d:downards-slpoe figure

e:Not enough evidence to support the fact that the quality of roads is the major factor that determines the number of alcohol-related deaths for making a fair comparison. Also, driving immature, and drunk driving would be the factors of alcohol-related deaths.

13 a:bell-shaped because most of households will be placed at left, but fewer high-income places on the right.

b:bell-shaped because most people have their scores on the range of middle.

c:right-skewed because the high-income group are minority.

d:left-skewed because most of Alzheimer’s patients are older-aged.

14 a:uniform because alcohol drinks are consumed in a constat rate besides the holidays.

b:left-skewed because an individual has to be a certain age to attend publich school

c:left-skewed because most patients with hearing-aid are older

d:bell-shaped because most full-grown men have average height, instead of having too short or too tall height.

hist(iris$Sepal.Length)