In: Statistics and Probability
1. A factory manufactures machines. Each machine is defective with probability 1/100, independently.
The machines get numbered 1, 2, . . . as they’re produced
(a) Out of machines 1, . . . , 1000, what is the probability that
none are defective?
(b) Out of machines 1, . . . , 1000, what is the probability that
two or fewer are defective? (c) Out of machines 1, . . . , 1000,
what is the probability that exactly ten are defective? (d) What is
the probability that the first defective machine is number
17?
(e) What is the probability the first defective machine is numbered
18 or higher?
1)
a)
Let X denote the number of defectives in the set. Then
Required probability =
b)
Let X denote the number of defectives in the set. Then
Required probability =
c)
Let X denote the number of defectives in the set. Then
Required probability =
d)
Required probability = P(first 16 are non-defective and 17th is defective)
=
e)
Required probability = P(first defective is numbered 18 or higher)
= P(18th is the first defective) + P(19th is the first defective) + P(20th is the first defective) + ....+P(1000th is the first defective)