A selection committee is to be chosen consisting of 5 ex-technicians. Now there are 12 representatives from four zones. It has further been decided that if Mr. X is selected, Y and Z will not be selected and vice-versa. In how many ways it can be done?	Choose the correct choice from the following answers.
A) 572	B) 672	C) 472	D) 372	E) None
Solution:   10C5: when both are not included.   10C4: when one of them is included.   Number of ways = 10C5 +10C4+ 10C4 = 672   Answer: Option 672
<result>B</result>
A selection committee is to be chosen consisting of 5 ex-technicians. Now there are 12 representatives from four zones. It has further been decided that if Mr. X is selected, Y and Z will not be selected and vice-versa. In how many ways it can be done?