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Select the outlier in the data set.\newline8,62,66,73,77,80,84,938, 62, 66, 73, 77, 80, 84, 93\newlineIf the outlier were removed from the data set, would the mean increase or decrease?\newlineChoices:\newline(A)increase\newline(B)decrease

Full solution

Q. Select the outlier in the data set.\newline8,62,66,73,77,80,84,938, 62, 66, 73, 77, 80, 84, 93\newlineIf the outlier were removed from the data set, would the mean increase or decrease?\newlineChoices:\newline(A)increase\newline(B)decrease
  1. Identify Outlier: Identify the outlier in the given data set: 8,62,66,73,77,80,84,938, 62, 66, 73, 77, 80, 84, 93. To find the outlier, we can use the interquartile range (IQR) method. First, we need to calculate the first quartile (Q1Q1), the third quartile (Q3Q3), and then find the IQR (Q3Q1Q3 - Q1). Any number that is more than 1.51.5 times the IQR below Q1Q1 or above Q3Q3 is considered an outlier.
  2. Calculate Quartiles: Since the data set is already in ascending order, we can find Q1Q_1 and Q3Q_3 by dividing the data set into four equal parts. For this data set, Q1Q_1 is the median of the first half, and Q3Q_3 is the median of the second half.\newlineThe first half of the data set: 88, 6262, 6666, 7373\newlineThe second half of the data set: 7777, 8080, Q3Q_300, Q3Q_311\newlineQ1Q_1 is the average of 6262 and 6666, and Q3Q_3 is the average of 8080 and Q3Q_300.\newlineQ3Q_388\newlineQ3Q_399
  3. Calculate IQR: Calculate the IQR: IQR=Q3Q1=8264=18\text{IQR} = Q3 - Q1 = 82 - 64 = 18.
  4. Determine Outlier Threshold: Determine the outlier threshold: Any number less than Q11.5×IQRQ1 - 1.5 \times IQR or greater than Q3+1.5×IQRQ3 + 1.5 \times IQR is an outlier.\newlineLower bound = Q11.5×IQR=641.5×18=6427=37Q1 - 1.5 \times IQR = 64 - 1.5 \times 18 = 64 - 27 = 37\newlineUpper bound = Q3+1.5×IQR=82+1.5×18=82+27=109Q3 + 1.5 \times IQR = 82 + 1.5 \times 18 = 82 + 27 = 109
  5. Identify Outlier: Identify the outlier: The number 88 is below the lower bound of 3737, so it is an outlier.
  6. Calculate Mean: Calculate the mean of the original data set: (8+62+66+73+77+80+84+93)/8=543/8=67.875(8 + 62 + 66 + 73 + 77 + 80 + 84 + 93) / 8 = 543 / 8 = 67.875.
  7. Remove Outlier: Remove the outlier (8)(8) and calculate the new mean: (62+66+73+77+80+84+93)/7=535/7=76.4286(62 + 66 + 73 + 77 + 80 + 84 + 93) / 7 = 535 / 7 = 76.4286.
  8. Compare Mean: Compare the original mean 67.87567.875 with the new mean 76.428676.4286 after removing the outlier. The new mean is higher than the original mean.

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