A supervisor records the repair cost for 17 randomly selected stereos. A sample mean of $\$ 66.34$ and standard devation of $\$ 15,22$ are subsequently computed. Determine the $80 \%$ conflidence interval for the mean repalr cost for the stereos. Assume the populotion is approximately normal.
Step 1 of 2: Find the critical value that should be used in constructing the confidence interval, Round your answer to three decimal places.
Answer
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Answer
The critical value that should be used in constructing the confidence interval is \(\boxed{1.282}\).
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 \(\boxed{1.282}\).
