1. I suspect that around 75% of my students will come to class each day (except for the exam dates.). How large sample do I need to ensure a 94% confidence with a margin of error of no more than 3%.
2. Amy is interesting in knowing whether there's a difference in how much the boys and girls spend on lunches at her school. She collected a sample of 28 boys from her school and they spent an average of $7.52 with standard deviation of $4.89. She also collected a sample of 15 girls from her school and they spent an average of $9.87 with standard deviation of $1.24. Construct a 95% confidence interval for the difference in the average spending for lunches of the boys and the average spending for lunches of the girls? Is your answer reliable? Why or why not?