SOLUTION: For a sample of 16 Philips light bulbs, the mean lifetime is 1250 hours with a standard deviation of 250 hours. For sample of 12 Liwanag light bulbs, the mean lifetime is 1400 hou

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Question 1182430: For a sample of 16 Philips light bulbs, the mean lifetime is 1250 hours with a standard deviation of 250 hours. For sample of 12 Liwanag light bulbs, the mean lifetime is 1400 hours with standard deviation of 300 hours. Use a 0.01 level of significance to test whether or not there is a significant difference between the average lifetimes of the two brands of light bulbs.
Thanks in advance!
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
this is a 2-way 2-sample t-test
Ho: P=L
Ha: P NE L
alpha=0.01
test is a t (0.99,df=26), reject for |t| > 2.779
t=(diff means)/ sqrt ((s1^2/n1)+(s2^2/n2))
=-150/ sqrt ((250^2/16)+(300^2/12)); denominator is sqrt(11406.25)
=-150/106.8
=-1.40
insufficient evidence to reject Ho
p-value = 0.17