The amount of fuel used by jumbo jets to take off is normally distributed with a mean of 4,000 gallons and a standard deviation of 125 gallons. A sample of 40 jumbo jets are randomly selected. What is...

The amount of fuel used by jumbo jets to take off is normally distributed with a mean of 4,000 gallons and a standard deviation of 125 gallons. A sample of 40 jumbo jets are randomly selected. What is the probability that the mean number of gallons of fuel needed to take off for a randomly selected sample of 40 jumbo jets will be less than 3,950 gallons? (Note: use standard error as the denominator of computing z-score)