The Standard Normal Distribution - Page 10

Questions
  • What are the median and the mode of the standard normal distribution?
  • What is the skewness of a normal distribution?
  • A placement exam for entrance into a math class yields a mean of 80 and a standard deviation of 10. How do you find the percentage of scores that lie between 60 and 80?
  • How can I tell if my data is normally distributed? Do the mean, median and mode have to be identical for it to be a normal distribution?
  • The resting heart rates for a sample of individuals are normally distributed with a mean of 70 and a standard deviation of 15. How do you find the percentage of heart rates less than 85?
  • Suppose that 40% of adult email users say "Yes." A polling firm contacts an SRS of 1500 people chosen from this population. If the sample were repeated many times, what would be the range of sample proportions who say "Yes"?
  • Given a normal distribution with mean = 100 and standard deviation = 10, if you select a sample of n = 25, what is the probability that x-bar is above 102.2?
  • What percent of scores will fall between –3 and +3 standard deviations under the normal curve?
  • Let z be a random variable with a standard normal distribution. Find the indicated probability. What is the probability that P(−0.61 ≤ z ≤ 2.50)?