method one - listing options
_y _ _ , 1*1*2*1=2
_ _ y _ , 2*1*1*1 OR 2*1*1*1 ==4
_ _ _ y , 3*2*1*1=6
total ways' count is (2+4+6)=12
method two - counting
fix y in the second place and count ways, 1 for w and 2C1 for other alphabets 1*2C1=2
fix y in the third place ~, 2 for w and 2C1 for other alphabets 2*2C1=4
fix y in fourth place ~, 3! ways for three alphabets=6
total ways's count is (2+4+6)=12
geet_ge wrote:In how many ways can you arrange 4 alphabets(w,x,y & z) in a straight line so that w comes before y?
