SOLUTION: Of 10 electric bulbs,three are defective but it not known which are defective. in how many ways can 3 bulbs be selected? how many of these selections will include at least one defe

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Question 702800: Of 10 electric bulbs,three are defective but it not known which are defective. in how many ways can 3 bulbs be selected? how many of these selections will include at least one defective bulb?
please explain it in step by step when doing the calculation.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Of 10 electric bulbs,three are defective but it not known which are defective. in how many ways can 3 bulbs be selected?
Ans: 10C3 = 120
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how many of these selections will include at least one defective bulb?
# that have NO defective is 7C3 = 35
# with at least one defective is 120-35 = 85
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Cheers,
Stan H.
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please explain it in step by step when doing the calculation.