Answer:
The 99% confidence interval for the mean commute time of all commuters in Washington D.C. area is (22.35, 33.59).
Step-by-step explanation:
The (1 - <em>α</em>) % confidence interval for population mean (<em>μ</em>) is:

Here the population standard deviation (σ) is not provided. So the confidence interval would be computed using the <em>t</em>-distribution.
The (1 - <em>α</em>) % confidence interval for population mean (<em>μ</em>) using the <em>t</em>-distribution is:

Given:

*Use the <em>t</em>-table for the critical value.
Compute the 99% confidence interval as follows:

Thus, the 99% confidence interval for the mean commute time of all commuters in Washington D.C. area is (22.35, 33.59).
It could also be 8.23592 x 10 ^ 5
Answer: B
Step-by-step explanation:
When you are multiplying exponents, if the base is the same, then you can directly add the exponents together.
We can see that both bases are 6. That means we can add the exponents.
[common denominator]
[add]

Now, we know that the answer will be
.