A box contains 8 lightbulbs of which 3 are defective.A bulb is selected from the box and tested.If it is defective,another bulb is selected and tested,until a nondefective bulb is chosen.Find the expected number E of bulbs chosen.
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![A box contains 8 lightbulbs of which 3 are defective.A bulb is selected from the box and tested.If it is defective,another bulb is selected and tested,until a nondefective bulb is chosen.Find the expected number E of bulbs chosen.](/uploads/image/z/8848082-2-2.jpg?t=A+box+contains+8+lightbulbs+of+which+3+are+defective.A+bulb+is+selected+from+the+box+and+tested.If+it+is+defective%2Canother+bulb+is+selected+and+tested%2Cuntil+a+nondefective+bulb+is+chosen.Find+the+expected+number+E+of+bulbs+chosen.)
A box contains 8 lightbulbs of which 3 are defective.A bulb is selected from the box and tested.If it is defective,another bulb is selected and tested,until a nondefective bulb is chosen.Find the expected number E of bulbs chosen.
A box contains 8 lightbulbs of which 3 are defective.A bulb is selected from the box
and tested.If it is defective,another bulb is selected and tested,until a nondefective
bulb is chosen.Find the expected number E of bulbs chosen.
A box contains 8 lightbulbs of which 3 are defective.A bulb is selected from the box and tested.If it is defective,another bulb is selected and tested,until a nondefective bulb is chosen.Find the expected number E of bulbs chosen.
同学,!难道你也在学AP统计?!
这是个典型的geometric distribution
一直重复实验直到第一次成功
E=1/p
p是成功概率,5/8
所以答案为8/5
如果要取整数的话是2