I need some help with a question below:
Three workers produce a certain part at the same rate .Joe averages 2 defective parts per hundred.Mary averages 5 defective parts per hundred.Harold averages 8 defective parts per hundred.The defective parts are identified by quality control and set aside in a rework pile.
How many defective parts do you expect there to be out of 1000 parts produced?
What is the probability that a randomly selected part in the rework pile was produced by Mary?
Break this question down into pieces.
If they each work at the same rate, they will produce the same # of units. So out of the 1000, it's pretty much divided up as 333, 333, 333.
The # of defective parts in those 3 groups will vary. The first 333 will have a defect rate of 2%. The second set will have a defect rate of 5%. And the third set will have a defect rate of 8%.
So how many defects are produced? Add them up. 2% of 333 + 5% of 333 + 8% of 333.
Once you have the total # of defects....look at that out of the total 1000 (or 999) items that were produced. What's the defect rate overall?
Hint: it should be some average between the 2%, 5% and the 8%.
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