SOLUTION: The probability that a life bulb will have a life time of more than 680 hours is 0.9788. The probability that a bulb will have a life time of more than 700 hours is 0.0051. Find t

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Question 1182589: The probability that a life bulb will have a life time of more than 680 hours is 0.9788. The probability that a bulb will have a life time of more than 700 hours is 0.0051. Find the probability that a bulb will last for more than 648 hours.
Answer by robertb(5830)   (Show Source): You can put this solution on YOUR website!
===> , or .

Similarly,
===> , or .

Now solve for and from the two equations above. The values would be

to 2 d.p., and to 2 d.p.

===> .

***We assume that lifetimes are normally distributed, and the probabilities were taken from https://stattrek.com/online-calculator/normal.aspx.

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