Given probability and mean and standard deviation for a normal distribution find z and confidence interval 7 3 a Intelligence quotient on a given test is normally distributed with a mean of 100 and a standard deviation of 10 Find the confidence interval for the intelligence quotient for the middle 95 of the population b Conifer tree ring widths in the rainforest of Washington are approximately normally distributed If the mean is 12mm and has a variance of 16 find a 98 confidence interval for the width of a conifer tree ring in a Washington state rain forest c We will assume the distribution of gestational blood glucose is approximately