Question

Ch 15 Probability(Std 10) Question 17

(1) a lot of 20 bulbs contain 4 defective ones one bulb is drawn at random from the lot what is the probability that this bulb is defective?

(2)Suppose the bulb drawn in no 1.. is not defective and is not replaced . what is the probability that this bulb is not defective ?​

Answer 1

Answer:

1. 1/5

2. 4/19

Step-by-step explanation:

1. There are total 20 bulbs and 4 of them are defective

So the probability of drawing a defective one is: 4/20 =1/5

2. Since a non defective bulb is removed,the total number of bulbs will become 19 and defective ones will remain 4, so the proper bulbs are 15 now

Now, the probability of drawing a defective one is: 4/19