(i) Here, total number of bulbs `= 20`
Number of defective bulbs `=4`
So, probability of drawing a defective bulb `= 4/20 = 1/5`
(ii)If drawn bulb is not defective and not replaced, then
Remaining number of total bulbs `= 19`
Remaining number of defective bulbs `=4`
So,remaining number of non-defective bulbs `=15`
Probability of drawing a non-defective bulbs `= 15/19`