Answer:
95% Confidence interval for the variance:

95% Confidence interval for the standard deviation:

Step-by-step explanation:
We have to calculate a 95% confidence interval for the standard deviation σ and the variance σ².
The sample, of size n=8, has a standard deviation of s=2.89 miles.
Then, the variance of the sample is

The confidence interval for the variance is:

The critical values for the Chi-square distribution for a 95% confidence (α=0.05) interval are:

Then, the confidence interval can be calculated as:

If we calculate the square root for each bound we will have the confidence interval for the standard deviation:

(a^3 - 2a + 5) - (4a^3 - 5a^2 + a - 2)
=a^3 - 2a + 5 - 4a^3 + 5a^2 - a + 2
= -3a^3 + 5a^2 - 3a + 7
Set up equal ratios
t/6=0.75/4.5 multiply both sides by 6
t=4.5/4.5
t=1 hour
So it will take Madison one hour to ride another six miles.
4,8,11,7 are the coefficients in this expression