In a box containing 60 bulbs, 6 are defective. What is the probability that out of a sample of 5 bulbs
(i) none is defective
(ii) exactly 2 are defective
(i) Using Bernoulli’s Trial P(Success=x) = nCx.px.q(n-x)
x=0, 1, 2, ………n and q = (1-p), n =5
The probability of success, i.e. the bulb is defective = p = 
q = 
probability of that no bulb is defective piece=
P(0 defective items) =
5C0.(
)0(
)5
⇒ (
5
(ii) Using Bernoulli’s Trial P(Success=x) = nCx.px.q(n-x)
x=0, 1, 2, ………n and q = (1-p), n =5
The probability of success, i.e. the bulb is defective = p = 
q = 
probability of that there are exactly 2 defective pieces=
P(2 defective items) =
5C2.(
)2(
)3
⇒ (
1