Final answer:
The value of a-b cannot be determined.
Step-by-step explanation:
To find the value of a-b, we need to determine the values of both a and b. The mean of the given set is 11, so the sum of all the numbers in the set is 11 multiplied by the total number of values, which is 6. This gives us the equation 13 + 7 + 22 + 6 + 4 + a = 11 * 6. Simplifying this equation, we get 52 + a = 66. Solving for a, we find that a is equal to 14.
The median of the set is represented by b. Since the set has an even number of values, the median is the average of the two middle values. The two middle values in the set are 7 and 22. Therefore, the median b is equal to (7 + 22) / 2, which is equal to 14.5.
Finally, we can find the value of a-b by subtracting the median b from the value of a. So, a-b = 14 - 14.5 = -0.5. Therefore, the answer is 5) cannot be determined.