7/4 you do this because, for example you can think of it like pizza and pizza slices. You have 1 pizza and 3/4 of a pizza, let’s say each slice is 1/4 of a pizza. How many slices do you have altogether? Seven. You can also think of 1 as 4/4, so the just add 3/4 + 4/4 (which is technically just 3+4) = 7/4
<span> The lower and upper bounds of the confidence intervals must be equally distanced from the mean so it will be </span><span>70.9 - 73.1 </span>hope it helps