Question

In a set of 12 devices 4 are defective. Assume that all of the defective and all of the functional devices are indistinguishable. How many linear orderings are there in which no two defective devices are consecutive

Answer 1

Answer: 126 orderings

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.

¹²⁻⁴⁺¹₄C

= ⁹₄C

= 126 orderings