Math HELP!!!!!
posted by angela
If light bulbs have lives that are normally distributed with a mean of
2500 hours and a standard deviation of 500 hours, what percentage of
light bulbs have a life less than 2500 hours?
A. About 25%
B. About 50%
C. About 75%
D. About 68%
Answer B

PsyDAG
Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability for the Z score. Multiply by 100. 
PsyDAG
Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability for the Z score. Multiply by 100.
However, if you realize that the mean and median are the same in a normal distribution, you won't need to go through all that work. 
PsyDAG
Sorry, I didn't see your answer. You are right.
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