Statistics students in Quebec Universities score 75.91 on average on a test of basic math
ability. The standard deviation of the test scores is 14.1415. If we choose 8 students at random and give
them the test, what is the exact probability that the mean of these 8 scores will be 70.00 or lower?
Solution :
Given that ,
mean = = 75.91
standard deviation = =14.1415
n=8
P(x < 70) = P[(x - ) / /n < (70-75.291) /14.1415/8 ]
= P(z < -1.06)
Using z table,
=0.1446
probability that the mean of these 8 scores will be 70.00 or lower=0.1446
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