you must reject a shipment if you find 4 defective units sup

you must reject a shipment if you find 4 defective units. suppose a shipment of 40 AC adapter has 8 defective and 32 nondefective units if you have a sample 12 AC adapters, what\'s the probability that

there will be no defective units ?

there will be at least one defective unit?

there will be 4 defective units?

the shippment will be accepted?

Solution

There are 40 and out of this 8 are defective

Prob for defective = p = 0.20

X - no of defectives follow a Binomial distribution, n = size of sample = 12

a) Prob no def = P(X=0) = 0.4096

b) Prob atleast one defective = P(X>=1) = 0.5904

c) Prob there will be 4 defective units = P(X=4) = 0.0016

d) Prob the shippment will be accepted = P(X>=4) = 0.0016