Question

tristan records the number of customers who visit the store each hour on a saturday. his data representing the first seven hours are 15, 23, 12, 28, 20, 18, and 23. how many customers visited the store during the eighth hour if the median number of customers per hour did not change?
16
19
20
23

Explanation:

Step1: Arrange the first - seven data in ascending order

$12, 15, 18, 20, 23, 23, 28$. Since there are 7 data points, the median is the 4th value, which is 20.

Step2: Consider the case with 8 data points

When there are 8 data points, the median is the average of the 4th and 5th ordered values. To keep the median 20, the new value must be such that when all 8 values are ordered, the average of the 4th and 5th values is still 20. If the new value is 20, when we order all 8 values, the 4th and 5th values will still average to 20.

Answer:

C. 20