a) If you increase your confidence level, does your confidence interval get bigger or smaller, and why? b) If you need a shorter condence interval and you're not allowed to change the confidence...

a) If you increase your confidence level, does your confidence interval get bigger or smaller, and why?

b) If you need a shorter condence interval and you're not allowed to change the confidence level, what can you do? Why does it work?

c) What does "95% confidence" mean?