Question

An open box will be made from a rectangular piece of cardboard that is 8 in. by 10 in. The box will be cut on the dashed red lines, removing the corners, and then folded up on the dotted lines. What is the MAXIMUM possible volume for the box?

A) 1.5 in3
B) 5.8 in3
C) 52 in3
D) 64 in3

Answer 1

C

Explanation:

The height, width, and length of the box will be (x)(8 - 2x)(10 - 2x). The volume of the box will be 4x3 - 36x2 + 80x = 0 Use a graphing calculator to graph the polynomial. Use the maximum feature to see the greatest volume the box can have. Be sure to set your window accordingly and think about what constraints are on the box. The maximum volume for the box is 52 in3. The cut would be 1.5 inches long. This is where the graph crosses the x-axis.

Answer 2

The correct answer is this one: "C) 52 in3."

Given the illustration, we can be able to know the dimensions of the formed box.

The dimensions are
Length: 10 - 2x
Width: 8 - 2x
Height: x

So the volume is
Volume = (10-2x) * (8-2x) * (x)
Let x = 2.5
Volume = (5) * (3) * (2.5) = 37.5
Let x = 2
Volume = (6) * (4) * (2) = 48
Let x = 1.5
Volume = (7) * (5) * (1.5) = 52.5
Let x = 1
Volume = (8) * (6) * (1) = 48
Let x = 0.5
Volume = (9) * (7) * (.5) = 31.5