to find the IQR you first need to write it in numerical order
77, 81, 83, 84, 86, 86, 88, 92
IQR is just Q3 - Q1
Q1 is the middle of the first have, since it has an even set of 4 numbers in the first half you need to take the average of the two middle ones.. which is 82
Q3 done the same process would be 87.
87 - 82 = 5
IQR = 5