Answer: 126 orderings
Step-by-step explanation:
Here let's suppose that total devices is given by n= 12
and defective ones are given by m= 4
Now, to find the number of orderings in which no two defective devices are consecutive is given by following relation.
¹²ā»ā“āŗĀ¹āC
= ā¹āC
= 126 orderings