Suppose the number of misspellings per page in a textbook from a population of world history textbooks are normally distributed with an unknown population mean and a population standard deviation of 0.97 misspellings. A random sample of history textbooks from the population produces a sample mean of x¯=4.9 misspellings. What value of z should be used to calculate a confidence interval with a 95% confidence level? z0.10 z0.05 z0.025 z0.01 z0.005 1.282 1.645 1.960 2.326 2.576

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.