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2-digit numbers less than 91 which are 1 less than a multiple of 10

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.

In which figure is de bc ? a. figure 1 b. figure 2 c. figure 3 d. figure 4