If a box has the shape of a rectangle prism with height 28 cm and the height is increased by 0.9, by how much does the surface area of the box increase

Question

A box has the shape of a rectangle prism with height 28 cm. If the height is increased by 0.9 cm, by how much does the surface area of the box increase. Show the work and a second way to solve and explain which way is better. So if the height is 28 cm and the width is 8.7 and length is 15 what is the answer

Answer 1

So, what does the surface area mean? If we take one side - any side - and find the area of that side, do the same for all the sides, then add them together, that's the surface area. It helps us figure out how much paint we need to paint the entire outside of something or how much wrapping paper we need to wrap a gift.

A rectanglar prism has 2 smaller sides of 8.7 x 15 = 130.5 cm² each, for a total of 2(130.5) = 261 cm².

You also have 2 sides that are 28 x 8.7 and 2 sides that are 28 x 15, right? (If you can find something in your house in the shape of a rectangular prism, it'll be easier to viualize).

Since you have 2 of every side, you could say...

A = 2(lw + hw + lh)

What happens, then, if 28 becomes 28.9? I bet you can figure it out from here!