Using the t-distribution to build the 99% confidence interval, it is found that:
- The margin of error is of 3.64.
- The 99% confidence interval for the population mean is (19.36, 26.64).
<h3>What is a t-distribution confidence interval?</h3>
The confidence interval is:

In which:
is the sample mean.
- s is the standard deviation for the sample.
The critical value, using a t-distribution calculator, for a two-tailed 95% confidence interval, with 21 - 1 = 20 df, is t = 2.086.
The other parameters are given as follows:

The margin of error is given by:

Hence the bounds of the interval are:


The 99% confidence interval for the population mean is (19.36, 26.64).
More can be learned about the t-distribution at brainly.com/question/16162795
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A. When you add to negative numbers, it is always negative. A positive + a positive is positive. In D, the answer is always 0. 1 + -1 is 0. In C, it varies. The bigger number not including the negative sign is the sign the number has. For example, -6 + 5 = -1. 6 is bigger than 5. You subtract the smaller number from the bigger number and that is the answer. You would then tack on the negative sign because it is -6, and 6 is bigger than 5.
The total interest earned is 40.75 and the final balance is 65.75
<u>Solution:</u>
Given, principle amount P = 25
Interest rate
Times compounded per year n = 12
Time in years t = 30

On substituting the values we get
![A = 25 [ 1+ \frac{0.0325}{12}]^{12\times30}= 25 [2.63]= 65.75](https://tex.z-dn.net/?f=A%20%3D%2025%20%5B%201%2B%20%5Cfrac%7B0.0325%7D%7B12%7D%5D%5E%7B12%5Ctimes30%7D%3D%2025%20%5B2.63%5D%3D%2065.75)
Interest I = A - P [since, A = P+I]

No you can not take the 4th root of a negative radicnd