Problem 12 in Chapter 9 described a study that examined the spotlight effect, which refers to people overestimating the extent to which others notice their appearance or behavior. In the study, n = 9 participants were asked to put on a Barry Manilow T-shirt and walk into a room where other students were working. Later, the participants were asked to estimate how many students in the room noticed the shirt. The average estimate for the nine participants was M = 6.4 with SS = 162.

a. Make a point estimate of the number of people that participants think noticed the shirt.

b. Compute the 90% confidence interval for the mean number of people.

c. After interviewing the students in the room, the researchers found that an average of ? = 3.1 students actually noticed the shirt. Based on this value and your answers from a and b, how much do people overestimate the number of others who notice their appearance.