Stats homework
A final exam in Math 10 has a mean of 73 and a standard deviation of 7.8. If 24 students are randomly selected, find the probability that the mean of their testscores is less than 76.
a. 0.7856 b. 0.5277 c. 0.8413 d. 0.9699
Homework Answers
μ=73
σ=7.8
n=24
P( xbar < 76 ) = P( (xbar-μ)/(σ/√n) < (76 - 73)/(7.8/√24) ) = P( z < 1.88 ) = 1 - .0301 = .9699
μ=73
σ=7.8
n=24
P( xbar < 76 ) = P( (xbar-μ)/(σ/√n) < (76 - 73)/(7.8/√24) ) = P( z < 1.88 ) = 1 - .0301 = .9699
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