Question

In a box containing 100 bulbs, 10 are defective. The probability that out of a sample of 5 bulbs, none is defective is(A) 10-1 (B) `(1/2)^5` (C) `(9/(10))^5` (D) `9/(10)` Select the correct answer from above options

Answer 1

Probablity of getting first non-defective bulb `= 90/100` Probablity of getting second non-defective bulb `= 89/99` Probablity of getting third non-defective bulb `= 88/98` Probablity of getting fourth non-defective bulb `= 87/97` Probablity of getting fifth non-defective bulb `= 86/96` So, probablity of getting all non-defective bulbs in a sample of 5 bulbs = `90/100**89/99**88/98**87/97**86/96` Closest option to this is option `C`.