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Bunuel
Machine–A produces 40% of the total output and Machine-B produces 60% of the total output. An average of nine units out of a thousand goods manufactured by Machine-A and one unit of 250 units produced by Machine-B prove to be defective. What is the probability that a unit chosen at random from the total daily output of the factory is defective?

A. 0.6
B. 0.06
C. 0.006
D. 0.0006
E. 0.00006

solved using weighted average
9/1000=0.009
1/250=4/1000=0.004
a=2/5, b=3/5
2/3=0.004-w/0.009-w,
0.002-18m=0.012-3m,
m=0.006

Ans (C)
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