The scores of students on the SAT college entrance examinations at a certain high school had a normal distribution with mean ?=531.7 and standard deviation ?=25.5
consider a simple random sample (SRS) of 30 students who took the test.
The standard deviation of the sampling distribution for ?¯ is?
What is the probability that the mean score ?¯ of these students is 536 or higher?
Solution :
The standard deviation of the sampling distribution for ?¯ is
= / n = 25.5 / 30 = 4.6556
P( 536) = 1 - P( 536)
= 1 - P[( - ) / (536 - 531.7) / 4.6556]
= 1 - P(z 0.924)
= 0.1777
Probability = 0.1777
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