Assume that the population standard deviation is know. What is the critical value you would find ( a $z$ or a $t$ )? Find the critical value used to make a $94 \%$ confidence interval?
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Step 1 ：The question is asking for the critical value used to make a 94% confidence interval. Since the population standard deviation is known, we would use a z-score, not a t-score. The z-score is a measure of how many standard deviations an element is from the mean. In this case, we need to find the z-score that corresponds to a 94% confidence interval.

Step 2 ：To find this, we need to remember that the confidence interval is centered around the mean, so a 94% confidence interval actually leaves 3% in each tail of the distribution (since 100% - 94% = 6%, and this 6% is split evenly between the two tails). Therefore, we need to find the z-score that leaves 3% in the tail.

Step 3 ：The critical value is approximately 1.8807936081512509.

Step 4 ：Final Answer: The critical value used to make a 94% confidence interval is approximately \(\boxed{1.88}\).