The perimeter of a rectangle is 2x+2y (width and length on both sides). so 2x+2y=220. Also x=y-2, because the width is 2 feet less than the length. Fill x=y-2 in 2x+2y=220 and we get 2(y-2)+2y=220. 2y-4+2y=220. 4y=216. y=54. Fill in y=54 in 2x+2y=220 and we get 2x+2(54)=220. 2x=220-2(54)=112. x=56.
The margin of error of a confidence interval has the following format:
In which z is related to the confidence level, is the standard deviation of the population and n is the size of the sample.
This means that the margin of error is inversely proportional to the size of the sample, which means that if the sample size increases, the margin of error decreases.
In this question, the sample size is increased, leading to a smaller margin of error. So the correct answer is given by option b.