What is the probability of this question?

Question

A bicycle factory runs two assembly lines, A and B. 94% of line A's products pass inspection and 89% of line B's products pass inspection. 40% of the factory's bikes come off assembly line B and the rest come off A. Find the probability that one of the factory's bikes did not pass inspection and came off assembly line B.

Answer 1

Let's suppose the factory produces 1000 bicycles: 600 from assembly line A, 400 from B. 94% of 600=564, 89% of 400=356. So 564+356=920 bicycles (92%) will pass inspection, on average. There are 80 faulty bicycles. 44 of these come off assembly line B. So 44/1000=4.4% is the probability that a bicycle from line B will not pass inspection.