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Select the outlier in the data set.\newline6,64,66,68,69,72,74,816, 64, 66, 68, 69, 72, 74, 81\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.\newline6,64,66,68,69,72,74,816, 64, 66, 68, 69, 72, 74, 81\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: 6,64,66,68,69,72,74,816, 64, 66, 68, 69, 72, 74, 81. To find the outlier, we can calculate the interquartile range (IQR) and then determine if any values fall more than 1.51.5 times the IQR above the third quartile or below the first quartile.
  2. Arrange Data Set: First, arrange the data set in ascending order, which is already done: 6,64,66,68,69,72,74,816, 64, 66, 68, 69, 72, 74, 81. Next, find the median (the middle value) of the data set. Since there are 88 numbers, the median will be the average of the 44th and 55th values: (68+69)/2=137/2=68.5(68 + 69) / 2 = 137 / 2 = 68.5.
  3. Find Median: Now, find the first quartile Q1Q_1, which is the median of the lower half of the data set (excluding the median of the entire data set if the number of data points is odd). The lower half is 6,64,66,686, 64, 66, 68. The median of this lower half is (64+66)/2=130/2=65(64 + 66) / 2 = 130 / 2 = 65.
  4. Find Q11: Find the third quartile (Q3Q3), which is the median of the upper half of the data set. The upper half is 6969, 7272, 7474, 8181. The median of this upper half is (72+74)/2=146/2=73(72 + 74) / 2 = 146 / 2 = 73.
  5. Find Q33: Calculate the interquartile range (IQR) by subtracting Q1Q1 from Q3Q3: IQR=Q3Q1=7365=8\text{IQR} = Q3 - Q1 = 73 - 65 = 8.
  6. Calculate IQR: Determine the lower bound for potential outliers by subtracting 1.51.5 times the IQR from Q1Q1: Lower Bound = Q11.5×IQR=651.5×8=6512=53Q1 - 1.5 \times IQR = 65 - 1.5 \times 8 = 65 - 12 = 53.
  7. Lower Bound: Determine the upper bound for potential outliers by adding 1.51.5 times the IQR to Q3Q3: Upper Bound = Q3+1.5×IQR=73+1.5×8=73+12=85Q3 + 1.5 \times IQR = 73 + 1.5 \times 8 = 73 + 12 = 85.
  8. Upper Bound: Any data point below the lower bound or above the upper bound is considered an outlier. In this case, the number 66 is below the lower bound of 5353, so it is an outlier.
  9. Identify Outlier: Now, to determine if the mean would increase or decrease upon the removal of the outlier, we need to compare the outlier to the current mean of the data set.\newlineFirst, calculate the mean of the original data set: (6+64+66+68+69+72+74+81)/8=500/8=62.5(6 + 64 + 66 + 68 + 69 + 72 + 74 + 81) / 8 = 500 / 8 = 62.5.
  10. Calculate Mean: Since the outlier 66 is much lower than the current mean 62.562.5, removing it will result in a higher mean because the remaining numbers are all higher than the original mean.

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