Question 1113611
 An ethanol railroad tariff is a fee charged for shipments of ethanol on public railroads. An agricultural association publishes tariff rates for​ railroad-car shipments of ethanol. 
Assuming that the standard deviation of such tariff rates is ​$1100​, determine the probability that the mean tariff rate of 250 randomly selected​ railroad-car shipments of ethanol will be within ​$100 of the mean tariff rate of all​ railroad-car shipments of ethanol. Interpret your answer in terms of sampling error.
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Find the z-value of the sample rates $100 below and $100 above the mean
of the sample means.
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lower z value = -100/(1100/sqrt(250)) = -1.4374
upper z value = +1.4374
Ans: prob = normalcdf(-1.4374,1.4374) = 0.849
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Cheers,
Stan H.
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