Justin and Hayley conducted a mission to a new planet Planet

Justin and Hayley conducted a mission to a new planet, Planet X, to study head size (they hypothesized that head size was correlated with brain size). They took a random sample of 100 Planet X residents and calculated a 95% confidence interval for the mean head circumference. What does a 95% confidence interval for head circumference tell you in this case? Select the best answer:

Question 5 options:

I am confident that most (95%) of all Planet X residents will have a head circumference within this interval

I am 95% confident that this interval includes the sample mean head circumference

I am 95% confident that this interval includes the mean head circumference of the Planet X population

The aliens are probably smarter than Justin and Hayley (uh oh)

I am 95% confident that most Planet X residents will have head circumferences within this interval

Solution

Answer: I am 95% confident that this interval includes the mean head circumference of the Planet X population