Statistics 1
Measures of central tendency
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Question 1
What is the mean in statistics?
Explanation
The mean is calculated by adding all numbers together and dividing by the count of numbers, which defines it as the average.
Question 2
Which measure of central tendency is defined as the value that appears most frequently in a data set?
Explanation
The mode is the value that occurs most frequently in a data set, distinguishing it from mean and median.
Question 3
When is the median the most appropriate measure of central tendency to use?
Explanation
The median, being the middle value, is less affected by outliers compared to the mean, making it more appropriate in these cases.
Question 4
What is the primary purpose of using measures of central tendency?
Explanation
Measures of central tendency help to summarize a set of data by finding the center or average, rather than analyzing its spread or predicting trends.
Question 5
In a skewed distribution, which measure of central tendency is often most affected?
Explanation
The mean is influenced by extreme values or outliers, which can skew the average away from the center of the majority of data.
Question 6
A teacher has the following test scores for her students: 85, 90, 78, 92, and 88. If she uses the mean as a measure of central tendency, what will be the result, and what does it indicate about the students' performance?
Explanation
The correct mean score calculation is (85 + 90 + 78 + 92 + 88) / 5 = 86.6. This indicates that, on average, students performed reasonably well, reflecting a balanced performance rather than skewed by high or low outliers. Other options misinterpret the mean's implication or miscalculate the value.
Question 7
In a recent research study, the researcher compiled the monthly sales figures of five stores: Store A $2000, Store B $2500, Store C $3000, Store D $1500, and Store E $3500. If the researcher decides to present the median as the measure of central tendency, which figure should he report, and why might this measure be preferred in this scenario?
Explanation
The median sales figure would be $2500 after ordering the data (1500, 2000, 2500, 3000, 3500). The median is preferred here as it provides a better representation of central tendency without being skewed by the extremities (like Store E's high sales). The other options miscalculate the median or misrepresent its significance.
Question 8
[Case Scenario] A teacher wants to understand the average performance of her class on a recent math test. The scores from her 10 students are as follows: 56, 67, 78, 85, 90, 92, 95, 67, 80, 88. To find the central tendency of these scores, she decides to calculate the mean score. What is the mean score of the class based on the given data? Question: Should the teacher proceed to use the mean as the measure of central tendency for this data set?
Explanation
The mean score of the students can be calculated by summing all the scores and dividing by the number of students. The scores add up to 848, which when divided by 10 gives an average (mean) of 84.8. The teacher's consideration of mean is appropriate as it reflects the average performance, and unless there are extreme outliers observed, this value tends to represent the data fairly well.
Question 9
[Case Scenario] A restaurant tracks the number of customers it serves each evening over a month to better understand its busiest periods. The customer counts for the month are as follows: 20, 22, 24, 20, 30, 35, 30, 25, 20, 22, 30, 50, 60, 20, 25, 30, 22, 20, 30, 30. After analyzing this data, the restaurant manager decides to calculate the mode to understand the most common number of customers served. What is the mode of the customer count for the month? Question: How should the manager interpret the mode to make business decisions about staffing?
Explanation
The mode in this case is 30, which means that the restaurant frequently serves 30 customers on several occasions. This information helps the manager determine peak periods for staffing, ensuring that servers are adequately available when the most customers are present, thereby optimizing service and potentially increasing sales.
Question 10
[Case Scenario] In a recent survey about daily exercise habits among a group of 12 participants, the data collected showed the following minutes of exercise per day: 15, 22, 33, 15, 40, 45, 50, 20, 35, 30, 25, 15. The health coach wants to summarize this data using the median to find an appropriate benchmark for how much exercise is common among the participants. Question: How would the health coach calculate the median, and what might this reveal about exercise habits in the group?
Explanation
To find the median of the exercise minutes, the health coach first lists the data in increasing order: 15, 15, 15, 20, 22, 25, 30, 33, 35, 40, 45, 50. Since there are 12 values (an even number), the median is calculated by averaging the 6th and 7th values (25 and 30), which results in a median of 27.5 minutes. This indicates that half the participants exercised less than this amount, providing insight into typical exercise habits within this group.