Question

There are 17 bulbs in a shop of which 5 are defective. If two bulbs are drawn randomly in succession without replacement, find the probability of getting both bulbs of the same quality by drawing a tree diagram. ​

Answer 1

Answer:

Here at least 2 items are defective out of 4. So the no. of defective items can be 2 or defective can be 3.

Total no. of defective ites =3

If 2 items are defective =3C2×7C2=63

If 3 items are defective =3C3×7C1=7

Probability that atleast 2 out of 4 items are defective =10C463+7=21070=31

Answer 2

Answer:

here

Five bulb are defective

so

no of bulb n(s)=17-5=12