Question

1 _A lot of 20 bulbs contain 4 defective onces. one bulb is drawn randam from the lot. what is the probability that this bulb is defected ?

2 _ suppose the bulb drawn in 1_ was not defected and not replaced from the rest what is probability that this bulb is not defected ? ​

Answer 1

$\huge \sf {\dag Answer }$

$\blue { \tt{Answer 1 }}$

Total number of bulb is 20 .

Number of all possible outcome = 20

Let, E = event of getting defective bulbs.

Then, The number of outcome favourable E = 4

Probability of selecting a defective bulb ,

${ \tt{ P (E) = \frac{4}{20} = \frac{1}{5} }}$

$\blue { \tt{Answer 2 }}$

Suppose one good is drawn and put outside .

Then, 15 good bulb and 4 defective bulbs are remaining in a lot .

Now, Total number of bulb = 19

Number of all possible outcome = 19

Let,

E1 = Event or selecting a good bulb

Then the number of outcome favourable to E1 = 15

Required Probability

${ \tt{ P ( E 1 ) = \frac{ 15 } {19}}}$