Production line probability problem > A manufacturer has six distinct motors in stock, two of which came from a particular supplier. The motors must be divided among two production lines, with three motors going to each line. If the assignment of motors to lines is random, find the probability that both motors from the particular supplier are assigned to the first line. I'd show my attempt but this stumbles me. I don't know what the number of outcomes in which the two from the particular supplier end up on the first line is, for example - nor the total outcomes.

Seee total ways of selecting for one of the lines is $${6\choose 3}$$ now we want both same motors in same line so they are fixed its just selecting $1$ from $4$ for last place so there are $4$ ways hence probability is $$\frac{4}{6\choose 3}=4/20=1/5$$