- In a sample with mean x = 12 and standard deviation s = 3.5, a data point at 16.8 would have what sample z-score?
A. 4.8 B. We can’t know the answer without knowing the population mean ? and standard deviation?. C. 1.4 D. 1.37
(16.8-12)/3.5 = 1.37
Answer D
Use the following data sample to answer the question.
4, 14, 6, 9, 21, 3, 7, 10
What is the median of this data sample?
A. There’s no median value.B. 9.25 C. 8 D. 7
Reorder the data: 3, 4, 6, 7, 9, 10, 14, 21
(7+9)/2 = 8
Answer C
- Which of the following statements is true about a stem-and-leaf plot?
A. It separates data at the decimal point, creating horizontal rows whose values are close together.
B. Stem-and-leaf plots are histograms whose bars have been arranged in decreasing order of frequency.
C. It involves creating columns of dots, one for each datum in the sample.
D. It uses vertical bars to illustrate a probability distribution.
Answer A is best, but not always correct
When creating a histogram, it’s important to ensure that the classes of data satisfy which properties?
A. They must include each interval on the number line.
B. They must be all the same size.
C. They must be mutually exclusive and exhaustive.
D. No requirements are made; the individual creating the graph is free to choose any classes.
Answer C
To answer the question, refer to the following data.
Ten students were sampled at random from a student population. Each was asked how many courses he or she was planning on studying in the upcoming year. The following is a list of the reported data values: 1, 2, 2, 3, 4, 5, 5, 5, 5, 6
What is the variance for the data values?
A. 1.687 B. 2.56 C. 1.6 D. 2.844
The correct answer is B, but to be consistent with the previous answer, the sample variance is 1.68652 = 2.844. My guess is that the questioner thinks D is correct. The questioner seems to incorrectly think that the standard deviation and variance of a set of numbers depends on whether the numbers are part of a sample.
Use the following data sample to answer the question.
4, 14, 6, 9, 21, 3, 7, 10
What is the range of this data sample?
A. 4 B. 18 C. 6 D. 10
21-3 = 18
Answer B
Which of the following involves inferential statistics as opposed to descriptive statistics?
A. A local cable system, using a sample of 500 subscribers, estimates that 40 percent of its subscribers watch a premium channel at least once per day.
B. A class of 50 statistics students earned an average grade of 73.5.
C. The Alcohol, Tobacco and Firearms department reported that Houston had 1,791 registered gun dealers in 1997.
D. The city business office reported 35 building permits for new single-family housing units.
Answer A
- A population is a collection of _______ about which we will measure certain characteristics or
properties, called _______.
A. data,numbers B.individuals, sample valuesC. experimental units, variablesD. people, traits
Answer C
LargeAirlines $4.36,6.19, -0.42,3.73,0.26,6.27 Small Airlines $1.60,-1.98,1.06,-0.21,-1.15 4.49,0.59,1.52,1.97,4.57,0.05
16. A study was conducted of the 12-month earnings per share for two categories of airline companies,with the result shown in the chart above.
Based on the data, which of the following statements is correct?
- The large airlines have a variance of 4.04, and the small airlines have a variance of 8.30.
- The large airlines have a mean earnings per share of 3.40, and the small airlines have a mean earnings per share of 1.22.
Once again there is a problem with the question because the mean, variance, and standard deviation can not be determined from a sample. I calculated the sample statistics below, and none of the options are correct.
Large airline sample average = (4.36+6.19-0.42+3.73+0.26+6.27)/6 = 3.40
Large airline sample variance = [4.362+6.192+0.422+3.732+0.262+6.272) – 6(3.402)]/5 = 8.301
Large airline standard deviation = sqrt(8.301) = 2.88
Small airline mean = (1.60-1.98+1.06-0.21-1.15+4.49+0.59+1.52+1.97+4.57+0.05)/11 = 1.14
Small airline variance = 1.602+1.982+1.062+0.212+1.152+4.492+0.592+1.522+1.972+4.572+0.052 – 11(1.142) = 4.233
Small airline standard deviation = sqrt(4.233) = 2.06
- Consider the following distribution:
Which of the following would you expect?
- The mean is less than the median, and the median is less than the mode.
- There’s no difference in the values of the mean, median, and mode.
- The mean is greater than the median, and the median is greater than the mode.
- The mean is greater than the mode, which in turn is greater than the median.
Incomplete question
- Which type of plot takes quantitative data and forms classes out of it, thus turning it into qualitative data?
- Histogram B. Dot plot C. Stem-and-leaf plot D. Pie chart
Answers A, B, and C