A process is in control and normally distributed with x control chart limits of 45 and 15. The subgroup size is 4. Suppose the process variance suddenly triples while process mean remains unchanged. What is the probability that the first subsequent subgroup average will fall outside the control limits? What are the probability and ARL? Suppose the process variance suddenly triples while process mean shifts downward to 10. What are the β probability and ARL now?

Step-by-step explanation:

We have been given a sum . We are asked to rewrite this sum using distributive property and greatest common factor.

First of all, we will find greatest common factor of 72 and 60.

Factors of 72: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72

Factors of 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60

We can see that the greatest common factor of 72 and 60 is 12.

We can rewrite our given sum as:

Upon factoring out 12, we will get:

Therefore, our required expression is .