Answer:

First, we need to arrange the data in order from lowest to highest.

H = {7, 9, 11, 12, 12, 15, 16}

We can see that there are 7 data points, so n = 7. Using the formula given, we can compute for Q1, Q2, Q3.

Q1 = (n+1)/4 = (7+1)/4 = 2

Q2 = 2(n+1)/4 = 2(7+1)/4 = 4

Q3 = 3(n+1)/4 = 3(7+1)/4 = 6

To compute for the interquartile range (IR), we can use the formula:

IR = Q3 - Q1

Substituting the computed values, we get:

IR = 6 - 2 = 4

Therefore, the values of Q1, Q2, Q3 and IR for the given set H are:

Q1 = 2

Q2 = 4

Q3 = 6

IR = 4