Question

A carton of 24 bulbs contain 6 defactive bulbs. One but is drawn at random. What is the probability that the bulbs is not defactive? If the bulb selected is defective nad it is not replaced and a second bulb ius selected at random from the rest, what is the probability that the second bulb is defactive?

Answer 1

Total number of bulbs, n(S)=24

Let `E_(1)`=Event of selecting not defective bulb=Event of selecting good bulbs
`n(E_(1))=18`
`therefore P(E_(1))=(n(E_(1)))/(n(S))=(18)/(24)=(3)/(4)`
Supposem the selected bulb is defective and not replaced then the total number of bulbs remains in a cartoon, n(S)=23.
In them, 18 are good bulbs and 5 are defective bulbs.
`therefore` P(selecting second defective bulb)=`(5)/(23)`