Question

In a lot (collection) of 100 light bulbs, there are 5 defective bulbs. an inspector inspects 10 bulbs selected at random. find the probability of finding at least one defec- tive bulb. hint: first compute the probability of finding no defectives in the sample.

Answer 1

Probability of finding no defective bulb
=95/100*94/99....86/91
=95!/(85!) / (100!/90!)
= 110983/190120
=>
Probability of finding at least one defective bulb
=1-110983/190120
= 79137/190120
= 0.41625 (to 5 decimal places)