Answer:
{x,y,z} = {-22/13,29/13,6/13}
Answer:
48 minutes
Step-by-step explanation:
Pete: 3 hours = 2 hours 60 minutes
Sheila: 2 hours 60 minutes - 55 minutes = 2 hours 5 minutes = 1 hour 65 minutes
Mark: 1 hour 65 minutes - 1 hour 17 minutes = 48 minutes
Split the shape in 3 rectangles
4x2=8x2= 16 ( the bottom and top rectangle)
6x2= 12 (middle rectangle)
16+12=28
Here is how to work 2, 3 , and 4.
Let h = height of the box,
x = side length of the base.
Volume of the box is

.
So

Surface area of a box is S = 2(Width • Length + Length • Height + Height • Width).
So surface area of the box is


The surface are is supposed to be the minimum. So we'll need to find the first derivative of the surface area function and set it to zero.

![4x = \frac{460}{ x^{2} } \\ 4x^{3} = 460 \\ x^{3} = 115 \\ x = \sqrt[3]{115} = 4.86](https://tex.z-dn.net/?f=%204x%20%3D%20%5Cfrac%7B460%7D%7B%20x%5E%7B2%7D%20%7D%20%20%5C%5C%20%204x%5E%7B3%7D%20%3D%20460%20%20%5C%5C%20x%5E%7B3%7D%20%3D%20115%20%20%5C%5C%20x%20%3D%20%20%5Csqrt%5B3%5D%7B115%7D%20%3D%204.86%20)
Then

So the box is 4.86 in. wide and 4.87 in. high.