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

$12,15,18,20,23,23,28$

Step2: Find the median of the first - seven data

Since there are 7 data points, the median is the 4th value. So the median of the first - seven data is 20.

Step3: Consider the new data set with eight values

When we add an eighth value, there will be 8 data points. The median of 8 data points is the average of the 4th and 5th ordered values. For the median to remain 20, the new value must be such that when the eight values are ordered, the average of the 4th and 5th values is still 20. If the new value is 20, when we order the eight - value data set, the 4th and 5th values (in the ordered set) will still average to 20.

Answer:

C. 20