A committe of three students has to be formed. There are five students: Jane, Joan, Paul, Stuart and Jessica. If Paul and Stuart refuse to in the committee together and Jane refuses to be in the committe without Paul, how many committee are possible?
If Jane is in the committee, then Paul is also present so we have
for the last place we have 2 options (Je and Jo) and one place i.e. 2C1 so for this selection 1*2 = 2 options
If P is there then we can have Jo, and Jes for the other two locations i.e
P:_: _ so two choice for two locations i.e. 1*2c2 = 1
I have not counted Jane here because then it will be the same as the first selection.
If stuart is there again then we can Je and Jo, we cant have Paul and Jane. so for this again 1 selection.
So the total are 4 selections.