SOLUTION: The average salary of graduates entering the actuarial field is reported to be $40,000. To test this, a statistics professor surveys 20 graduates and finds their average salary to

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Question 1158634: The average salary of graduates entering the actuarial field is reported to be $40,000. To test this, a statistics professor
surveys 20 graduates and finds their average salary to be $43,228. Assume the population is normally distributed with a
population standard deviation is $4000. Using 𝛼 = 0.05, has he shown the reported salary to be incorrect?

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Random sample and other assumptions assumed
Ho: salary if $40000
Ha: it is not
alpha=0.05 p{reject Ho|Ho true}
test stat is a z=(xbar-mean)/sigma/sqrt(n)
reject if |z|>1.96
=(3228)/4000/sqrt(20)
z=3.61
reject Ho p-value<0.0004
the reported salary is not $40,000