A rectangular piece of cardboard 9" x 12" is made into an open box by cutting a 2 1/2" square from each corner and bending up the sides. Find the volume of the box if no allowance is made for overlapping of the edges.

4*7*2.5 = ?

why use 4 x 7

Cutting 2.5 inches from each end of the cardboard:

9 - 5 = 4
12 - 5 = 7

ok , thank you

You're welcome.

To find the volume of the box, we must first find the dimensions of the box after the corners are cut and the sides are folded up.

Since a square with sides of length 2 1/2" is cut from each corner, the length and width of the resulting box will be reduced by 2 1/2" on each side.

The new length of the box will be 9" - (2 * 2 1/2") = 9" - 5" = 4".

The new width of the box will be 12" - (2 * 2 1/2") = 12" - 5" = 7".

Now that we have the dimensions of the box, we can find the volume by multiplying the length, width, and height.

The height of the box will be the height of the squares that were cut from the corners, which is 2 1/2".

Therefore, the volume of the box is 4" * 7" * 2 1/2" = 70 cubic inches.

Therefore, the correct answer is option a. 70 cu. in.