mukherjeeabhish
There are 6 tasks and 6 persons. Task 1 cannot be assigned either to person 1 or to person 2; task 2must be assigned to either person 3 or person 4. Every person is to be assigned one task. In how many ways can the assignment be done?
(A) 144
(B) 189
(C) 192
(D) 368
(E) 378
As TASK 2 can be assigned to either person 3 or 4 ,let's start with it.
Let task 2 goes to person 3 .
Then choices left for task 1 are Person 4,5,6 = 3
Rest of the tasks can be assigned in a non-restrictive way (4 task remaining and 4 person= 4! or 4 *3*2).
so total for this case = 3 * 4*3*2 = 72
Similarly 72 when task 2 goes to person 4 .
So total = 144 .Option A
I agree with your approach
Task 2 can be assigned in 2 ways
The previous assignment restricts the possibilities for task 1 to 3
Finally, there are 4 people that can be assigned to 4 tasks, thus ----> 2 * 3 * 4! = 6 * 4 * 3 * 2 = 144 -----> A