HW 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 2 5 2 4 2 5 1 5 2 3 0 The variance of restaurant visits is calculated to be 2.75. What is the standard deviation of restaurant visits per week? (Please, round your solution to at least 2 decimal places).
1.66
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 2 5 2 4 2 5 1 5 2 3 0 What is the median number of restaurant visits 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 2 5 2 4 2 5 1 5 2 3 0 What is the mode in the sample? (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 - 6 1 - 4 2 - 2 3 - 2 4 - 8 5 - 3 What is the mean number of MacBook Air laptops sold per day? (Round your answer to 3 decimal places)
2.44
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 2 5 2 4 2 5 1 5 2 3 0 What is the mean number of restaurant visits in the sample? (Please, do not round your answer).
2.75
In 2009, the average donation to the Help Way was $450 with a standard deviation of $42. In 2010, the average donation was $309 with a standard deviation of $38. 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 2010 because the coefficient of variation is larger for that year.
2010 and larger
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 2 5 2 4 2 5 1 5 2 3 0 What is the range of restaurant visits per week? (Please, do not round your answer).
5
Without Wait Tracking System With Wait Tracking System 33 - 33 27 - 18 25 - 17 77 - 32 25 - 19 34 - 22 33 - 37 29 - 16 34 - 21 32 - 12 30 - 26 33 - 19 Comparing values of the mean, the median and the standard deviation for the offices with and without a tracking system, what would you say about efficiency in accommodating patients of the offices with a wait tracking system (compared to the offices without a tracking system)?
A tracking system helps accommodating patients in a more efficient way which is supported by the lower average and median wait times, as well as the lower standard deviation of the waiting times
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
Without Wait Tracking System With Wait Tracking System 33 - 33 27 - 18 25 - 17 77 - 32 25 - 19 34 - 22 33 - 37 29 - 16 34 - 21 32 - 12 30 - 26 33 - 19 Consider patients with a wait time of 32 minutes in the samples of offices with and without a wait tracking system (10th and 4th patient in the data, respectively). Comparing z-scores for these two patients, what would you conclude?
Even though the wait time is the same for these patients, the z-scores are different because the patients belong to the samples with different means and standard deviations.
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, median, and mode
Which of the following symbols represents the standard deviation of the population?
O
Without Wait Tracking System With Wait Tracking System 33 - 33 27 - 18 25 - 17 77 - 32 25 - 19 34 - 22 33 - 37 29 - 16 34 - 21 32 - 12 30 - 26 33 - 19 Do the data for offices with and without a tracking system contain outliers? Hint: that's where you want to use the z-scores.
Only the data for the offices without a tracking system contain outliers
Which of the following is the most influenced by outliers?
Range
Which one of the following statements is true for a right-skewed distribution?
The mean is greater than the median.
Which of the following symbols represents the mean of the sample?
X with a line on top of it
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.
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 positive value
The mean of the sample
can be negative, positive or zero
Comparing the consistency (variability) between two data sets when their means are very different is best done with the
coefficient of variation
Since the population is always larger than the sample, the value of the sample 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 when all items are arranged in ascending order
When outliers are present in the data set, which measure is the best to describe central tendency in the data?
median
Which measure would you use to describe central tendency for qualitative data?
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 greater than zero
U is an example of a
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 includes only some subjects of interest in the study
The median is defined as the
the middle point of the data set
If two groups of numbers have the same mean, then
their medians can be different
Which of the following statements is NOT true concerning the attributes of the z-score?
z-score can be positive or negative for data values above the mean of the distribution
