Question

5. A box contains 4 defective bulbs and 16 good bulbs. When a bulb is picked from the box, what is the probability that it is a a. defective bulb b. good bulb
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Answer 1

Answer:

Total no. of bulbs =20

No. of defective bulbs =4

Therefore,

P(getting a defective bulb)=

total no. of bulbs

No. of defective bulbs

=

20

4

=

5

1

Now,

One non defective bulb is drawn then the total numbers of bulb left is 19

Total numbers of bulbs =19

No. of defective bulbs =4=4

No. of non-defective bulbs =19−4=15

P(bulb is not defective)=

total numbers of bulbs

No. of non-defective bulbs

=

19

15