SOLUTION: Suppose that 50 identical batteries are being tested. After 8 hours of continuous use, assume that a given battery is still operating with a probability of 0.70 and has failed with
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Question 1124794: Suppose that 50 identical batteries are being tested. After 8 hours of continuous use, assume that a given battery is still operating with a probability of 0.70 and has failed with a probability of 0.30.
What is the probability that fewer than 25 batteries will last at least 8 hours? Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! The mean would be 35 batteries (50*0.7)
The variance would be 10.5 (mean*0.3)
The sd would be sqrt (10.5) or 3.24
the continuity correction factor would be z<(24.5-35)/3.24 of z< 10.5/3.24 =3.24
probability is 0.0006
Check 50C24*0.7^24*0.3^26=0.000592
50C23*0.7^24*0.3^27=0.00016
the others will be far smaller.
