Question: how to calculate confidence interval lower and upper bound?
Answer: You can find the upper and lower bounds of the confidence interval by adding and subtracting the margin of error from the mean. So, your lower bound is 180 - 1.86, or 178.14, and your upper bound is 180 + 1.86, or 181.86. You can also use this handy formula in finding the confidence interval: x̅ ± Za/2 * σ/√(n).