In a box of switches, it is known that 10% of the switches are faulty. A technician is wiring 30 circuits,
each of which needs one switch. What is the probability that (a) all 30 work (b) at most two of the
switches do not work.
2
Let the random variable represent the number of faulty switches then, given as,
a)
To find the probability that all 30 switches work is equivalent to finding the probability that there are no faulty switches. This can be written as,
The probability that all 30 switches work is 0.04239116
b)
The probability that there are at most 2 faulty switches is 0.4113512
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