The mean life of a type of light bulb is μ = 800 hours. the standard deviation is ό = 120 hours. Find probability that the sampling error in a sample of 100 bulbs is less than 18 hours.
please列出計算步驟和explain !!!
probability ( sampling error ) question
2007-05-23 12:45 pm
回答 (2)
2007-05-23 10:58 pm
✔ 最佳答案
According to Central Limit Theorem, normal distribution can be approximated if sample size is large enough (>30)z = 18 / (120 / 100^.5)
z = 18 / (12)
z = 1.5
from normal distribution table, 0.4332 is found for z=1.5
Since it is to find out the probability of sampling error less than 18 hours, i.e. +18 hours, we need to find out the probability for z between -1.5 to 1.5, and so
the probability of sampling error less than 18 hours
= 0.4332 * 2
= 0.8664
2007-06-01 12:42 am
1/2, I guess
收錄日期: 2021-04-18 22:13:30
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