Statistics HW 2
What is the unit of measurement for the variance you calculated above? $ It does not have unit of measurement cents $^2
$^2
A sample of twelve families was taken. Each family was asked how many times per week they dine in restaurants. Their responses are given below. 2 1 0 2 0 2 1 2 0 2 1 2 What is the median number of restaurant visits in the sample? (Please, do not round your answer).
1.5
A sample of twelve families was taken. Each family was asked how many times per week they dine in restaurants. Their responses are given below. 2 1 0 2 0 2 1 2 0 2 1 2 What is the mode in the sample? (Please, do not round your answer).
2
A sample of twelve families was taken. Each family was asked how many times per week they dine in restaurants. Their responses are given below. 2 1 0 2 0 2 1 2 0 2 1 2 What is the range of restaurant visits per week? (Please, do not round your answer).
2
The following table shows a frequency distribution of the number of MacBook Air laptops sold per day at a particular Best Buy: Number of Laptops Frequency 0-------------------------2 1--------------------------1 2-------------------------4 3-------------------------5 4-------------------------2 5-------------------------2 What is the mean number of MacBook Air laptops sold per day? (Round your answer to 3 decimal places)
2.625
In 2009, the average donation to the Help Way was $225 with a standard deviation of $45. In 2010, the average donation was $400 with a standard deviation of $60. In which year did the donations show a more dispersed distribution? Hint: to answer this question, you need to calculate the coefficient of variation for each year. The donations show a more dispersed distribution in ___________ ["2009", "2010"] because the coefficient of variation is _________ ["larger", "smaller"] for that year.
2009, larger
Using the sample data, it was computed that the 60th percentile for this data is $143.4. Calculated 60th percentile is best interpreted as: Middle 60% of gift-buyers spend less than $143.4 for the Mother's Day 60% of all gift spending for the Mother's Day are below $143.4 60% of all gift spending for the Mother's Day are above $143.4 Middle 60% of gift-buyers spend on average $143.4 for the Mother's Day
60% of all gift spending for the Mother's Day are below $143.4
Using the sample data, it was computed that the 3d quartile for this sample equals $161.5. This is best interpreted as: 25% of spending for the Mother's Day are below $161.5 The average for the middle 75% of spending for the Mother's Day equals $161.5 Middle 75% of spending for the Mother's Day are below $161.5 75% of spending for the Mother's Day are below $161.5
75% of spending for the Mother's Day are below $161.5
How do we find the median if the number of observations in a data set is odd? By taking the middle value in the sorted data set By averaging the first and the third quartiles By taking the middle value in the sorted data set after eliminating outliers By averaging the minimum and maximum values
By taking the middle value in the sorted data set
The Boom company has recently decided to raise the salaries of all employees by 10%. Which of the following is(are) expected to be affected by this raise? Mean and mode only Mode and median only Mean and median only Mean, median, and mode
Mean, median, and mode
If two groups of numbers have the same mean, then their modes must also be equal None of the suggested alternatives is correct their medians must also be equal their standard deviations must also be equal
None of the suggested alternatives is correct
The mean of the sample can never be negative None of the suggested alternatives is correct is always smaller than the mean of the population from which the sample was taken can never be zero
None of the suggested alternatives is correct
Using the sample data, it was computed that the z-score for a data value of $166 is 0.96. Calculated z-score is best interpreted as: Spending of $166 is 96% above the mean spending Spending of $166 is 0.96 standard deviations away from the mean Spending of $166 is 0.96 standard deviations above the mean spending Spending of $166 is 0.96 above the mean spending
Spending of $166 is 0.96 standard deviations above the mean spending
Which one of the following statements is true for a right-skewed distribution? The mean is greater than the median. The mean is roughly equal to the median. The mean is greater than the mode. The mean is less than the median.
The mean is greater than the median.
Which of the following symbols represents the mean of the sample?
Xbar
Is it possible for a data set to have more than one mode? Yes, if two or more values in a data set occur with the most frequency. Yes, if two or more values in a data set occur the same number of times. No, there must always be a single mode, or else there is no mode. Yes, if there are at least two different values in a data set, there is always more than one mode.
Yes, if two or more values in a data set occur with the most frequency.
The standard deviation of a sample of 100 elements taken from a very large population is determined to be 60. The variance of the population can be any value greater than zero cannot be larger than 60 must be at least 100 cannot be larger than 3600
can be any value greater than zero
Comparing the consistency (variability) between two data sets when their means are very different is best done with the median z-score standard deviation coefficient of variation
coefficient of variation
Since the population is always larger than the sample, the value of the sample mean is always smaller than the true value of the population mean could be larger, equal to, or smaller than the true value of the population mean is always equal to the true value of the population mean is always larger than the true value of the population mean
could be larger, equal to, or smaller than the true value of the population mean
If a data set has an even number of observations, the median is the average value of the two middle items cannot be determined must be equal to the mean is the average value of the two middle items when all items are arranged in ascending order
is the average value of the two middle items when all items are arranged in ascending order
Which of the following is the most influenced by outliers? Mean 75th percentile Median 1st quartile
mean
When outliers are present in the data set, which measure is the best to describe central tendency in the data? mean median standard deviation weighted mean
median
The median is defined as the average of a data set middle point in a data set the closest value to the mean most frequent value of a data set
middle point in a data set
Which measure would you use to describe central tendency for qualitative data? mean mode weighted mean median
mode
During a cold winter, the temperature stayed below zero for ten days (ranging from -20 to -5). The variance of the temperatures of the ten-day period must be positive cannot be computed since all the numbers are negative is negative since all the numbers are negative can be either negative or positive
must be positive
Which of the following symbols represents the standard deviation of the population?
o
M is an example of a population variance mode sample statistic population parameter
population parameter
If the variance of a data set is correctly computed with the formula using n - 1 in the denominator, which of the following is true? the data set is a population the data set could be either a sample or a population the data set is a sample the data set includes all subjects of interest in the study
the data set is a sample
Which of the following statements is NOT true concerning the attributes of z-scores? z-scores are equal to zero for data values equal to the mean of the distribution z-scores are negative for data values below the mean of the distribution z-scores can be positive or negative for data values above the mean of the distribution z-scores are positive for data values above the mean of the distribution
z-scores can be positive or negative for data values above the mean of the distribution
A sample of twelve families was taken. Each family was asked how many times per week they dine in restaurants. Their responses are given below. 2 1 0 2 0 2 1 2 0 2 1 2 What is the mean number of restaurant visits in the sample? (Please, do not round your answer).
1.25
A sample of twelve families was taken. Each family was asked how many times per week they dine in restaurants. Their responses are given below. 2 1 0 2 0 2 1 2 0 2 1 2 The variance of restaurant visits is calculated to be 0.75. What is the standard deviation of restaurant visits per week? (Please, round your solution to at least 2 decimal places).
.87
