Question

1. Suppose you select 35 measurements taken from a simple random sample of something.

(a) What would happen to the mean, variance, and standard deviation of your measurements, if you multiplied all 35 of them by 3? Explain.

(b) What would happen to the mean, variance, and standard deviation of your measurements, if you added 3 to each of them, instead of multiplying them all by 3? Explain.

2. Confidence Intervals.

(a) Why do we need confidence intervals? Isn't a sample mean good enough by itself?

(b) If you increase your confidence level, does your confidence interval get bigger or smaller, and why?

(c) If you need a shorter confidence interval and you're not allowed to change the confidence level, what can you do? Why does it work?

(d) What does "95% confidence" mean? Explain

Answer 1