An automatic machine that fills bags of unpopped popcorn is operating properly if the weights are independently and normally distributed with a mean of 114 grams and a standard deviation of 4.9 grams. Find the probability that if 7 bags are randomly selected, their mean weight exceeds 115 grams.
statistics - MathGuru, Wednesday, November 7, 2012 at 5:24pm
z = (x - mean)/(sd/√n)
With your data:
z = (115 - 114)/(4.9/√7)
Finish the calculation.
Next, check a z-table to find probability using the above z-score.
I hope this will help get you started.