Answer: 26
Step-by-step explanation:
Let us re arrange the data in ascending order to find the median.
11, 11 , 12 , 12 , 13 , 13 , 13 , 15 , 18
The mode is the number with the highest frequency , from the data , 13 appears three times , which is more than the appearance of the other numbers , therefore , 13 is the mode.
Median is the middle number , therefore , the median is 13
So, the sum of the mode and median = 13 + 13
= 26
