The mean IQ of a randomly selected student from a specific university is ; its variance is 150. A psychologist wants to estimate . To do so, for some n, she takes a sample of size n of the students at random and independently and measures their IQs. Then she finds the average of these numbers. How large a sample should she choose to make at least 92% sure that the average is accurate within 3 points?

STAT-5615: Statistics in Research I Lecture 10 z-tests for Proportions Ott & Longnecker Ch 10.2, 10.3 Dr. Christian Lucero Virginia Tech Fall 2016 One Sample Hypothesis Test for the Population Proportion Many applications in health related research involve population proportions. I What proportion of the population smoke cigarettes I What proportion of the population has health insurance Estimating the population proportion (p) is similar to estimating the population mean. A sample is drawn and the sample proportion p is computed. Under the Central Limit Theorem, the sample proportion, p , has an approximate normal distribution with a mean p and a standard error r p(1▯