Question

A box contains 90 good and 10 defective screws. if 10 screws are drawn without replacement, the probability that none of them is defective is

Answer 1

Total no. of screws = 10
No. of good screws = 90
No. of defective screws = 10
In that 100 screws, 10 screws are drawn
Therefore
No. of possible outcomes = 10
Total no. of outcomes in such a case that none of them are defective = 90

Probability = No. of possible outcomes/Total no. of outcomes
                  = 10/90
                  = 1/9

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