Chapter 01 - Overview & descriptive Statistics

W E B Q U I Z : Devore, Probability and Statistics for Engineering & the Sciences Chapter 1

QUIZ

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Fill in the blank. When the information of interest is available for all subjects or objects in the population, we have a ________.

a. statistic

b. variable

c. sample

d. census

Suppose a sample of ten students is taken from a statistics class and their first test score is recorded. The data set is 75, 89, 95, 65, 78, 80, 77, 98, 45, and 70. What type of data set is described?

a. Multivariate

b. Population

c. Bivariate

d. Univariate

Which of the following is the branch of statistics that includes techniques for generalizing conclusions from a sample to a population?

a. descriptive statistics

b. inferential statistics

c. multivariate statistics

d. probability

Which of the following is an example of a descriptive statistic?

a. The mean of a sample.

b. All of these choices.

c. A boxplot of a set of data.

d. A scatter plot of two variables.

If a firm is interested in taking a sample of 100 employees from all employees who participate in a 401K plan, what is the sampling frame?

a. The sampling frame cannot be determined from the information given.

b. The sampling frame consists of all employees at the firm regardless if they participate in the 401K plan.

c. The sampling frame consists of all employees at the firm that participate in the 401K plan.

d. The 100 individuals sampled constitute the sampling frame.

Which of the following is the definition of a simple random sample?

a. In a simple random sample, every subject or object has an equal chance of being selected from the sample.

b. In a simple random sample, the population units are separated into nonoverlapping groups and a sample is taken from each one.

c. In a simple random sample, every sample of size n has an equal chance of being selected from the sampling frame.

d. In a simple random sample, each sample of size n has a different probability of being selected from the sampling frame.

Which of the following cannot be conveyed using a stem-and-leaf plot?

a. The spread of the data set.

b. The order in which the observations were obtained.

c. The presence of any gaps in the data.

d. The presence of any outlying values.

How many peaks does the following stem-and-leaf plot from MINITAB display?

a. It shows one peak.

b. It shows five peaks.

c. It shows two peaks.

d. It shows six peaks.

Which of the following conclusions regarding the dotplot below is correct? The dotplot was obtained using MINITAB.

a. The sample size is 4.

b. The data point at 900 appears to be an outlier.

c. The value that occurs most often in the sample occurs only at 400.

d. There are two peaks in the data set.

10.

A variable is ________ if its set of possible values consists of an entire interval on the number line.

a. multivariate

b. random

c. continuous

d. discrete

11.

Which class interval has the largest number of observations in the histogram below?

a. The intervals for 1.09.

b. The question cannot be answered with the information given.

c. The intervals for 1.10.

d. The intervals for 1.04, 1.05, 1.08 and 1.13.

12.

Suppose a sample of ten students is taken from an engineering class and their first test score is recorded. The data set is 98, 80, 65, 89, 95, 65, 78, 77, 35, and 70. What is the sample mean for the data collected?

a. 75.2

b. 752

c. 77.5

d. 65

13.

Suppose the size of aneurysm in patients is measured for a clinical study to determine the effects that size has on other health issues. What is the median size of aneurysm for the following sample of 8 patients? Sample data in centimeters: 7, 6, 9, 5, 3, 10, 4, and 11.

a. 6.5

b. 6

c. 4

d. 6.875

14.

If a categorical variable is measured such as gender where x represents the number of individuals that are female in a sample of size n, then what proportion of the sample is male?

15.

If a sample has 100 observations and the researcher is interested in computing a 5% trimmed mean, how many observations will be removed from the sample to calculate ?

a. fifty observations

b. zero observations

c. five observations

d. ten observations

16.

Which of the following is a measure of variability?

a. Range

b. Median

c. Proportion

d. Mean

17.

Which of the following conclusions is correct for the two variables, PO₂ and PCO₂, graphed below?

a. The standard deviation for PCO₂will be smaller than the standard deviation for PO₂.

b. The range for PCO₂will be larger than the range for PO₂.

c. The variances will be approximately equal for PO₂ and PCO₂.

d. The variance for PO₂will be smaller than the variance for PCO₂.

18.

What is the value of for any given set of data?

a. 0

b. The sample data must be known to calculate this value.

c. 1

19.

If the sample standard deviation for the weight of a sample of ten boxes of light bulbs is 1.05 pounds, what is the variance for this set of data?

a. 1.02 pounds

b. 1.05 pounds

c. 1.10 pounds

d. 0.105 pounds

20.

Using the following data set of temperatures recorded in an experiment, what is the five-number summary needed to create a boxplot of the data set? Sample data: 70, 80, 85, 65, 90, 65, 82, 60, 92, 95, 110

a. {60, 65, 82, 92, 110}

b. {70, 85, 65, 92, 110}

c. {70, 78, 81.3, 87.8, 110}

d. {60, 67.5, 82, 91, 110}

21.

What shape does the histogram below represent?

a. The histogram is negatively skewed.

b. The histogram is unimodal.

c. The histogram is bimodal.

d. The histogram is symmetric.

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