Answer:
The answer is 87.
Explanation:
First, line up the data in order: 81, 83, 91, 94. Next, take off the numbers at the ends until you reach the middle number. Since there is no middle number in this problem, you have to find out the middle of 83 and 91 by lining them up in order: 83, 84, 85, 86, 87, 88, 89, 90, 91. The answer would then be 87.