Final answer:
In order to find the first quartile, the data needs to be sorted in ascending order. The position of the first quartile is found using the formula (N+1)/4. For these data, the first quartile is the average of the 5th and 6th data points, resulting in 1988.5 million dollars.
Step-by-step explanation:
To calculate the first quartile, or the 25th percentile, we must first sort the sales data in ascending order. Once sorted, you can find the first quartile by finding the median of the lower half of the data. The formula to locate the position of the first quartile, Q1, is (N+1)/4, where N is the total number of observations. Once you know the position, you can find the exact value at that location(if the position is an integer) or a value between the two nearest numbers(if the position is a fraction).
With 21 data points, we find the position of Q1 to be (21+1)/4 = 5.5. This means the first quartile is midway between the 5th and 6th observations in the ordered list of sales. Since the 5th and 6th data points after arranging in ascending order are 1850 and 2127 respectively, we can use the average of these two figures, which is (1850+2127)/2 = 1988.5.
So, the first quartile of sales, in millions of dollars, is 1988.5 million dollars.
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