Answer: D. 38
You have the correct answer. Nice work
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Step-by-step explanation:
If the values aren't sorted, then list them from smallest to largest. The values are already sorted for us, so we move onto the next step.
That next step is to find the median. The median is 29 because four values are smaller than it, and four values are larger than it. The value 29 is right in the middle. This value is in slot 5.
Next, split the data into two halves where L = {21,24,25,28} is the lower half and U = {35,37,39,42} is the upper half. As you can see, any value in set L is smaller than the median. While any value in set U is larger than the median.
The third quartile is the median of set U. We have four values in this set, so the median will be between slots 3 and 4 (between 37 and 39)
Average 37 and 39 to get (37+39)/2 = 38. We see that 38 is the midpoint of 37 and 39.
Therefore, the third quartile is 38.