The mean of the new data set is greater than the mean of the original data set, and the median of the new data set is greater than the median of the original data set.
The mean of the new data set is greater than the mean of the original data set, and the medians of the two data sets are equal.
The mean of the new data set is less than the mean of the original data set, and the median of the new data set is less than the median of the original data set.
The mean of the new data set is less than the mean of the original data set, and the medians of the two data sets are equal.
Explanation
Correct answer: B.
Choice B is correct. The mean of a data set is the sum of the values in the data set divided by the number of values in the data set. The new data set consists of the weights of the tortoises in the original data set and one additional weight, . Since the additional weight, , is greater than any of the values in the original data set, the mean of the new data set is greater than the mean of the original data set. If a data set contains an odd number of data values, the median is represented by the middle data value in the list when the data values are listed in ascending or descending order. Since the original data set consists of the weights of tortoises and is in ascending order, the median of the original data set is represented by the middle value, or the th value. Based on the frequencies shown in the table, the th value in this data set is . If a data set contains an even number of data values, the median is between the two middle data values when the values are listed in ascending or descending order. Since the new data set consists of the weights of tortoises, the median of the new data set is between the th and th data values when the values are arranged in ascending order. To keep the data in ascending order, the additional value of would be placed at the bottom of the frequency table with a frequency of . Therefore, based on the frequencies in the table, the th and th values in the new data set are both . It follows that the median of the new data set is , which is the same as the median of the original data set. Therefore, the mean of the new data set is greater than the mean of the original data set, and the medians of the two data sets are equal.
Desmos solution:
Note: Adding 39 raises the mean, and the cumulative counts place both the 36th and 37th weights at 17, so the median stays 17.
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect and may result from conceptual or calculation errors.
Choice C
Choice C is incorrect and may result from conceptual or calculation errors.
Choice D
Choice D is incorrect and may result from conceptual or calculation errors.
Student discussion
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