<PRE><B>Question 1169805</B>
--------D--------ND-----Total
B1------7--------343----350
B2-----12--------388----400
B3-----2.5-------247.5---250
--------21.5------978.5--1000

probability defective is 2.15% skewed towards the left a little consistent with B1 and B2 predominating. 
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not defective is the complement or 97.85%
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if defective, made by B3 is 2.5/21.5 or 11.63% probability
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if not defective, 343/978.5 made by B1 or 35.05%</PRE>