How to find the probability using normal distribution.
The New York Times reported that is the mean time to download the home page for the internal Revenue Service (IRS), was 0.8 second. Supposing that the download time was normally distributed with a standard deviation of 0.2 sec. If you excellent a random sample of 30 download times
a) Explain what is the probability that the sample mean is less than 0.75 second?
b) Explain what is the probability that the sample mean is between 0.70 and 0.90 sec?
c) The probability is 80% that is the sample mean is between what two values and symmetrically distributed around the population mean?
d) The probability is 90% that is the sample mean is less than what value?