Suppose we model light bulb lifetimes as having normal distribution with mean and standard deviation 500 and 50 hours, respectively.
Find the value of d such that 30% of all light bulbs have lifetime more than d.
as top 30% will fall at 70th percentile:
for 70th percentile critical value of z= | 0.52 | ||
therefore corresponding value d=mean+z*std deviation= | 526.00 hours |
Suppose we model light bulb lifetimes as having normal distribution with mean and standard deviation 500...
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Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57 hours and a standard deviation of 3.5 hours. With this information, answer the following questions. (a) What proportion of light bulbs will last more than 61 hours? (b) What proportion of light bulbs will last 51 hours or less? (c) What proportion of light bulbs will last between 59 and 61 hours? (d) What is the probability that a randomly selected light bulb lasts...
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