Check out the picture I've got the full explanations on there
Hope it's clear
Answer:
1. Three things influence the margin of error in a confidence interval estimate of a population mean: sample size, variability in the population, and confidence level. For each of these quantities separately, explain briefly what happens to the margin of error as that quantity increases.
Answer: As sample size increases, the margin of error decreases. As the variability in the population increases, the margin of error increases. As the confidence level increases, the margin of error increases. Incidentally, population variability is not something we can usually control, but more meticulous collection of data can reduce the variability in our measurements. The third of these—the relationship between confidence level and margin of error seems contradictory to many students because they are confusing accuracy (confidence level) and precision (margin of error). If you want to be surer of hitting a target with a spotlight, then you make your spotlight bigger.
For question 3, you needn't worry about the number of total students asked. The question is really just asking you what's 45% as a fraction, which is 9/20. This is because 45% = 45/100, divided by 5 = 9/20.
For question 6, just substitute in the values. So you do 4(7 × 4 - 3 × -7), which gives you 4(28 - -21). Two minuses make a plus, so it's just asking you to do 4 × 49 (because 28 + 21 = 49). The answer is 196.
