a box contains 20 electric bulbs , out of which 4 are defective . 2 bulbs are chosen at random from this box . The probability that at least one of these is defective is

a box contains 20 electric bulbs , out of which 4 are defective . 2 bulbs are chosen at random from this box . The probability that at least one of these is defective is Correct Answer 5/19

Non defective electric bulb এর সংখ্যা = 16C2 /20C2 = 120/190 = 12/19 কমপক্ষে 1 টি defective bulb পাবার সম্ভাব্যতা = 1 - 12/19 = 19 - 12/19 = 7/19
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