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The average high temperatures in degrees for a city are listed.

58, 61, 71, 77, 91, 100, 105, 102, 95, 82, 66, 57

If a value of 82° is changed to 94°, which of the following measures changes the most and what is the new value?

IQR 34°
Range 48°
Mean 81.4°
Median 84°

1 Answer

4 votes

Answer:

If we change the value of 82° to 94°, the new data set becomes:

58, 61, 71, 77, 91, 100, 105, 102, 95, 94, 66, 57

IQR:

To find the new interquartile range (IQR), we first need to find the new values of the first quartile (Q1) and the third quartile (Q3). The median of the original data set is 84°, which is between the 6th and 7th values when the data is ordered. So, the first half of the data set consists of the values 58, 61, 71, 77, 82, and 91, and the second half consists of the values 94, 95, 100, 102, 105.

The new Q1 is the median of the first half of the data set, which is (71 + 77) / 2 = 74. The new Q3 is the median of the second half of the data set, which is (100 + 102) / 2 = 101.

The new IQR is Q3 - Q1 = 101 - 74 = 27.

Range:

The range is simply the difference between the largest and smallest values in the data set. Before the change, the range was 105 - 57 = 48. After the change, the range is 105 - 58 = 47.

Mean:

To find the new mean, we add up all the temperatures and divide by the number of temperatures. Before the change, the sum was 980 and there were 12 temperatures, so the mean was 980/12 = 81.7° (rounded to one decimal place). After the change, the sum is 982 and there are still 12 temperatures, so the new mean is 982/12 = 81.8° (rounded to one decimal place).

Median:

The median is the middle value in the data set when it is ordered. Before the change, the median was 84°. After the change, the median is still 84°, since only one value was changed and it did not affect the position of the median.

Therefore, the IQR changes the most, increasing from 34° to 27°. The new value of the IQR is 27.

User Youssef Liouene
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