1) The attention span of a two year-old is normally distributed with a mean of about 9 minutes and a standard deviation of 1.75 minutes. Suppose we randomly survey 60 two year-olds. What is the probability that a two year old has an attention span of more than 8.5 minutes?
2) Toastmasters International cites a February 2001 report by Gallop Poll that 40% of Americans fear public speaking. A student believes that less than 40% of students at her school fear public speaking. She randomly surveys 426 schoolmates and finds that 150 report they fear public speaking. Conduct a hypothesis test at the 5% level of significance to determine if the percent at her school is less than 40%.
Show your hypothesis your calculated z or t score and your decision to accept or not accept the null hypothesis.