A normal distribution of data has a mean of 15 and a standard deviation of 4. How many standard deviations from the mean is 25?
For a standard normal distribution, if , what is the value of ?

About what percentage of the data lies within 2 standard deviations of the mean in a normal distribution?
Which of the following probabilities is equal to approximately 0.2957? Use the portion of the standard normal table below to help answer the question.zProbability0.000.50000.250.59870.500.69150.750.77341.000.84131.250.89441.500.93321.750.9599




The probability that a random variable is greater than or equal to z standard deviations from the mean in a standard normal distribution is p%. What can be said with certainty about the probability that the random variable is less than or equal to –z standard deviations from the mean?
Which of the following statements is equivalent to ?





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