Question 1051027
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Hi  
n = 25, x&#772; = 640, s = 30
Ho: u = 650 
Ha: u < 650
a) mean
We are using the T distribution because 
1) we do not know the population standard deviation (very common in most cases)
2) n < 30
(b) Is the test a right-tailed, left-tailed or two-tailed test?  left-tailed
(c) t = (640-650)/(30/5) = -10/6 = -5/3 = -1.6667
(d)P(t < -1.6667), DF 24 = .0543 
(d) .0543 > .05
there is not sufficient evidence to justify the rejection of Ho at the &#945;=0.05 level