# Answer to Question #26805 in Statistics and Probability for lojain

Question #26805

a box containing 20 spark , of which 6 are defective , if tow plugs are selected from the box without replacement , what is the probability that both will be defective?

Expert's answer

So, we have a box with 20 sparks: 14 are ok and 6 are defective (according to the problem statement).

Selection of two plugs is the independent process: we select the first one and then the second.

So, we have 20*19=380 variants to make a choice.

To have both defective we have 6*5=30 variants.

So the probability that both we took from the box are defective is P= (defective variants)/(all the variants)=30/380=3/38~0.08 (or 8%)

Selection of two plugs is the independent process: we select the first one and then the second.

So, we have 20*19=380 variants to make a choice.

To have both defective we have 6*5=30 variants.

So the probability that both we took from the box are defective is P= (defective variants)/(all the variants)=30/380=3/38~0.08 (or 8%)

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