5. How does the construction of a confidence interval differ depending on whether you know the population standard deviation or whether you must estimate the population standard deviation? 6. The t--distribution has a shape that differs from the shape of the normal distribution. a) How does this difference affect the size of e confidence interval constructed using a t rather than a z? b) How does sample size affect this difference? 7. The effect of a new behavioral therapy on depression (as measured by the Beck Depression Inventory) is being investigated. How might an experimenter demonstrate that, on average, the reduction in Beck Depression Inventory scores is 20 points or more? 8. Heights for 14--year--old boys and girls were calculated. The mean height for the sample of 12 boys was 174 cm with s = 62. For the sample of 12 girls, the mean was 166 cm with s-= 65. Construct the 95% confidence intervals for the