The lifetime of 100 watt light bulbs is normally distributed with a mean of 750
ID: 3044347 • Letter: T
Question
The lifetime of 100 watt light bulbs is normally distributed with a mean of 750 hours and a standard deviation of 20 hours. Owing to strict quality control during the manufacturing process, 95% of the bulbs will last at least 717.1 hours while 75% of the bulbs will last at most 763.5 hours. If a 100 watt bulb is selected at random, what will be its expected lifetime (in hours)?
(Hint: What is the expected value of a Random Variable?)
743.3
717.1
763.5
751.7
750
1.743.3
2.717.1
3.763.5
4.751.7
5.750
Explanation / Answer
expected lifetime (in hours)
Expected value would be 763.5, option C is Correct
Option C is Correct
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