For 80 guests you will need 80/10 = 8 times more than for 10 guests:
8*9.50 = $76
Refreshment for 80 guests costs $76.
Answer:
The 99% confidence interval for the mean peak power after training is [299.4, 330.6]

Step-by-step explanation:
We have to construct a 99% confidence interval for the mean.
A sample of n=7 males is taken. We know the sample mean = 315 watts and the sample standard deviation = 16 watts.
For a 99% confidence interval, the value of z is z=2.58.
We can calculate the confidence interval as:

The 99% confidence interval for the mean peak power after training is [299.4, 330.6]
The anwer is 3. The volume of a cube is lwh. 3 x 3 x 3 = 27
Forgive me but they deleted my answer for it did not have any work to be shown providing you know how to do Algebra you get X= 12 as your outcome. <span />