In recent years home lighting technology has changed dramatically due to the development of Light Emitting Diode (LED ) bulbs. Although previously used mainly in traffic lights and although LED bulbs are more expensive than incandescent bulbs, they use approximately 90% less energy and they last up to 25 times longer than incandescent bulbs. It has been estimated that the average home saves $250 per year using LED bulbs rather than incandescent bulbs. One popular manufacturer of LED bulbs claim that nearly all of their 75-watt LEDs will last for more than 25,000 hours. - Suppose that a small company purchases 200 of these 75-watt LEDs with a guarantee that 95% of them will last for more than 25,000 hours. Assuming the guarantee is correct, what is the probability that at least 190 of them will last for more than 25,000 hours? -Suppose that a small company purchases 400 of these 75-watt LEDs with a guarantee that 99% of them will last for more than 25,000 hours. Assuming the guarantee is correct, what is the expected number of them that will last for more than 25,000 hours?

Linear Algebra: A Modern Introduction
4th Edition
ISBN:9781285463247
Author:David Poole
Publisher:David Poole
Chapter7: Distance And Approximation
Section7.3: Least Squares Approximation
Problem 35EQ
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In recent years home lighting technology has changed dramatically due to the development of Light Emitting Diode (LED ) bulbs. Although previously used mainly in traffic lights and although LED bulbs are more expensive than incandescent bulbs, they use approximately 90% less energy and they last up to 25 times longer than incandescent bulbs. It has been estimated that the average home saves $250 per year using LED bulbs rather than incandescent bulbs. One popular manufacturer of LED bulbs claim that nearly all of their 75-watt LEDs will last for more than 25,000 hours.

- Suppose that a small company purchases 200 of these 75-watt LEDs with a guarantee that 95% of them will last for more than 25,000 hours. Assuming the guarantee is correct, what is the probability that at least 190 of them will last for more than 25,000 hours?

-Suppose that a small company purchases 400 of these 75-watt LEDs with a guarantee that 99% of them will last for more than 25,000 hours. Assuming the guarantee is correct, what is the expected number of them that will last for more than 25,000 hours?

 
 
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