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it has been reported that the average life for lightbulbs is 4000 hours. Learnin

ID: 3267415 • Letter: I

Question

it has been reported that the average life for lightbulbs is 4000 hours. Learning of this, a plant manager suspects that the temperature conditions have an adverse effect on the life of bulbs. In a test involving 15 bulbs in various locations, the average life was 3882 hours and a standard deviation of 200 hours. assume normal distribution and use 0.025 significance. do the test results support the manager's suspicion?

- I believe H1u<4000 but the chegg solution says H1 u is not equal to 4000. Am i wrong or is chegg wrong? If i am wrong, please explain why

Explanation / Answer

Here

H0: mu>=4000

Vs

H1: mu< 4000

Because we want to test whether the temperature conditions have an harmful (adverse) effect on life of the bulb .