Over a long period the proportion of defective items in a ma

Over a long period the proportion of defective items in a manufacturing process is 5%. In a random sample of 25, find the probability a) no defectives b)exactly two defectives c)more than two defectives d) Mean and standard deviation

Solution

probability of defective = 5% 0f 25 = 1.25/25 = 0.05

hence probability of non dfective = 0.95

a)25C0*(0.05)^0*(0.95)^25 = 0.277

B) TWO DEFECTIVE = 25C2*(0.05)^2*(0.95)^23 = 0.230

C) MORE THEN TWO DEFECTIVE = 1 - P(0) - P(1) - P(2)

1 - 0.277 - 0.230 - 0.364 =0.129

D) MEAN AND STANDARD DEVIATION CAN BE FOUND IN THE SIMILAR WAY