If a normal distribution has a mean of 10 and standard deviation of 1, then what proportion of the distribution of means falls between 9 and 11 when sample size is 2? A sample of 1939 scores was drawn from a normal distribution with a mean of 19.45 and a standard deviaiton of 12.04. What was the sample mean if exactly 25.25% of the distribution of means falls below it? If za/2 = 2.3125, determine the proportion of (1-a)100% confidence intervals that will not capture u when the confidence intervals are computed as m + za/2(0m)? A population is known to be normally distributed with o = 17.88. A sample of 13 scores randomly selected from the population was found to have a mean of m = 69. Calculate the lower limit of the 85% confidence interval about m