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# Statistics Problem Watch

1. Hi there guys wondering if you could help me out here;

'A quality control manager found that 30% of work-related problems occured on Mondays and 20% in the last hour of a days shift. It was also found that 4% of worker-related problems occurred in the last hour of Mondays shift.

- What is the probability that worker related problem that occurs on a Monday does not occur in the last hour of the days shift?

I am confused as to where the 4% is conditional i.e. problem in last hour given it is monday, or is it simply problem on monday and in the last hour.

Thanks for any solutions.
2. The 4% means problem on monday AND in the last hour.

You can solve this problem by drawing a venn diagram - use a circle for monday and a circle for last hour. Work out the probabilities for each region then find the answer to the final question by using the definition of conditional probability.

The final question is asking for the probability that the problem is not in the last hour GIVEN THAT it's on monday.
3. Thanks very much

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Updated: December 25, 2010
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