A company has developed a new type of lightbulb, and wants to estimate its mean lifetime. A simple random sample of 81 bulbs had a mean lifetime of 585.6 hours with a standard deviation of 28 hours.
a. Calculate the standard error and round your answer to 1 decimal place: ________________
b. Use StatCrunch to find a 95% confidence interval: _______________________
c. Interpret what your confidence interval means in the context of this problem.
d. If the company was hoping that the population mean was 600 hours, is that likely based on your confidence interval?
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