# introductory statistics homework problem help

1.

The newspaper reports that higher rates of sunburn and ice cream consumption correspond. Does that mean that eating ice cream can put you at risk of sunburn? What might be the reason behind this phenomenon?

a. Kids are not waiting 40 minutes after eating to swim

b. In summer both ice cream consumption and rates of sunburn increase

c. Eating ice cream is viewed as a replacement for sunblock

2.

A prospective graduate student may be interested in class size at the university s/he will attend. Data on how many students were in last years incoming class is an example of:

a. Descriptive statistics

b. Inferential statistics

3.

A random sample is one ______

a. That is haphazard

b. That is unplanned

c. In which every unit of a particular size has an equal probability of being selected

d. That ensures that there will be no uncertainty in the conclusions

4.

True or False? A sample of only those students seated in the front row of class would be an unbiased sample.

a. True

b. False

5.

Stratified sampling___

a. Can be more representative than simple randomized sampling

b. Can be used if the population has a number of distinct groups

c. Is done by randomly sampling from subgroups in a way that is proportional to their size in the population

d. All of the above

6.

The following distribution has:

a. A positive skew

b. A left skew

c. No skew

7.

A normal or bell shaped distribution has its greatest probability density in the middle.

a. True

b. False

8.

Which of the following is a qualitative variable?

a. Weight in pounds

b. Number of days of precipitation

c. Race

d. Average daily high temperature

9.

In an experiment on the effect of exercise on memory, the independent variable is __(choose only one answer)

a. Number of hours of exercise

b. Recall score on a memory test

c. Gender of the subjects

d. Gender of the experimenter

10.

A continuous variable is

a. One that can take on any value in a certain range

b. One that can only take on a finite number of values

11.

For the scores 3, 5, 8, 10, 14, 17, 21, 25, calculate the 75th percentile using the following formula: R = P/100 x (N + 1)

a. 6.75

b. 17

c. 21

d. 20

12.

Identify the scale of measurement for the following: temperature measured in centigrade

a. Nominal

b. Ordinal

c. Interval

d. Ratio

13.

For the following data,

a. 1

b. 16

c. 49

d. 7

14.

Converting total time taken to complete a race to speed by dividing distance by time involves a linear transformation.

a. True

b. False

15.

Log10(10,000)=

a. 100,000

b. 104

c. 4

d. none of the above

16.

According to the text, Pie charts are effective for displaying the relative frequencies of only ______ categories. They are not recommended, however, when you have a _______ number of categories.

a. A few, large

b. many, small

17.

The lowest value in the dataset is (multiply stems by 10.0):

a. 19

b. 13.2

c. 13

d. 1.9

18.

Stem and leaf displays are good for comparing three groups.

a. True

b. False

19.

The text recommends that bar charts are better at showing means than box plots.

a. True

b. False

20.

Line graphs should be avoided when the variable on the X-axis is a qualitative variable.

a. True

b. False

21.

Based on the frequency polygon displayed below, the second-most common test grade was around what score?

a. 35

b. 85

c. 95

d. 175

22.

Response times were generally longer to the:

a. Large target

b. Small target

23.

Bar charts are NOT particularly useful for showing change over time.

a. True

b. False

24.

The following bar chart shows percent increase in the consumer price index for four three-month periods ending the date shown:

In which quarter did the CPI increase the most, in percentage terms?

a. the quarter ending July 2000

b. the quarter ending October 2000

c. the quarter ending January 2001

d. the quarter endinig April 2001

25.

In a histogram, frequencies are represented by_______

a. Lines

b. Bars

c. Portions of the pie

d. Leaves

26.

For the following histogram of test scores,

The majority of scores came between______

a. 39.5 and 49.5

b. 89.5 and 99.5

c. 79.5 and 89.5

d. 159.5 and 169.5

27.

For the following line graph of quarterly percentage changes in five components of the CPI, which component steadily increased from quarter to quarter?

a. Housing

b. Medical Care

c. Food and Beverage

d. Recreation

e. Transportation

28.

For the following stem and leaf plot, how many numbers are there between 2 and 3?

Multiply the stem by 1.

4|33

3|56

2|00456

1|00134

0|1245589

-0|0679

-1|005559

-2|7

a. 0

b. 2

c. 5

d. 15

29.

For the following box plot, E represents:

a. The upper hinge

b. The median

c. The mean

d. A far out value

30.

For the following box plot, G represents:

a. The lower hinge

b. The lower adjacent

c. The lower inner fence

d. The 75th percentile

31.

A Biased sample is one that ______

a. Is too small

b. Will always lead to a wrong conclusion

c. Will likely have certain groups from the population over-represented or under-represented due only to chance factors

d. Will likely have certain groups from the population over-represented or under-represented due only to systematic sampling factors

32.

The area under the curve of a probability distribution is _____

a. 0

b. 100

c. .68

d. 1

33.

A discrete variable is _____

a. One that can take on any value in a certain range

b. One that can only take on a finite number of values

34.

Which of the following is a qualitative variable?

a. Weight in kilograms

b. Number of days without precipitation

c. Ethnicity

d. Average daily temperature

35.

The highest value in the dataset is (multiply stems by 10.0):

a. 132

b. 13.2

c. 13

d. 1.32

36.

Stem and leaf displays are good for comparing two groups.

a. True

b. False

37.

For the following box plot, A represents:

a. The upper hinge

b. The upper adjacent

c. An outside value

d. A far out value

38.

Low-density lipoprotein (LDL) is an important part of blood cholesterol test. LDL higher than 130mg/dl is a risk factor of developing cardiovascular disease. To prevent cardiovascular disease, a health center had a free blood cholesterol test for all the people older than 65 in the community. A total of eight people attended the blood screening and their blood test results are listed below:

LDL(mg/dl): 130,143,114,110,123,110,134,124

After the blood test, the nurse wants to know the variance of LDL scores

39.

Rachael and Peter are discussing how the mean value and variance affect the distribution graph. As the following graph shows, there are two distributions: A and B

Peter said that the distribution A has fatter tail because its has bigger standard deviation than the distribution B. Rachael’s answer is different:she thinks the distribution A has a smaller standard deviation than the distribution B.

Who do you think is right?

a. Peter

b. Rachael

c. None of them are right. Distribution A and Distribution B have the same standard Deviation

40.

What is the best measure of central tendency for the following set of numbers? 98,78,56,23,587

a. Mean

b. Mode

c. Median

d. Standard Deviation