Step 1 :To find the critical value for constructing the confidence interval, we need to use the Z-score table because the population is approximately normal. The Z-score for an 80% confidence interval is found by looking up the value corresponding to 1 - ((1 - 0.80) / 2) = 0.90 in the Z-table.
Step 2 :The critical value that should be used in constructing the confidence interval is \(\boxed{1.282}\).