# math

posted by .

Mia is stacking copies of a new book in a square-pyramid display by the front window of her bookstore. for each consecutive layer, she places one book where four meet.
A. I the bottom row of the display has 144 books and there is one book on the top, determine how many rows of books are in her pyramid.
B. Explain how to find the total number of books in the display.
C. If she removes the top four rows, how many books are left in the pyramid display?

• math -

You might want to make a sketch to show that the bottom level is a 12 by 12 square
the second level is a 11 by 11 square, etc

So your sum is 12^2 + 11^2 + 10^2 + ... 2^2 + 1^2

you could just add up these numbers to get 650
or you could use a formula that says
the sum of squares of consecutive numbers from 1 to n is
n(n+1)(2n+1)/6 which gives us 650

for the last part, find the sum of books removed at the top and subtract that from 650

btw, did you realize that the books would have to be square in shape?

## Similar Questions

1. ### math

A book is 1 3/4 inches thick. There are 8 copies of the same book stacked in a bookstore. How tall is the stack in inches?
2. ### math

A book is 1 3/4 inches thick. There are 8 copies of the same book stacked in a bookstore. How tall is the stack in inches?
3. ### algebra2

you are creating a window display at a toy store using wooden blocks. the display involves stacking blocks in triangular forms. you begin to display with 1 block, which is your first "triangle," and then stack three blocks, two on …

A display of cans on a grocery shelf consists of 20 cans on the bottom, 18 cans in the next row, and so on in an arithmetic sequence, until the top row has 4 cans. How many cans, in total, are in the display?
5. ### help

a store does a display of 200 balls, he places them in the shape of a square pyramid. the bottom layer has 64 balls for each consecutive layer of balls, one ball is placed where 4 balls meet. how may layers will be in the pyramid?
6. ### math

One shelf at Cover-to-Cover Bookstore contains copies of several books on the best-seller list. Half of the books on the shelf are copies of the Number 1 best- seller. Of the remainder, 1/4 are copies of the Number 3 book. The rest …
7. ### math

A store manager set up a cardboard display to advertise a new brand of perfume. The display is a square pyramid whose base is 18 inches on each side. The height of each triangular face of the pyramid is 12 inches. How much cardboard …
8. ### Math

A store manager set up a cardboard display to advertise a new brand of perfume. The display is a square pyramid whose base is 18 inches on each side. The height of each triangular face of a puramid is 12 inches. How much cardboard …
9. ### Math, algebra 2

You are stacking soup cans for a display in a grocery store. Your manager wants you to stack 120 cans in layers, with each layer after the first having one less can then they layer before it. One can should be in the top layer. If …
10. ### math

Book 1 255 book 2 235 book 3 178 book 4 299 book 5 150 book 6 67 book 7 82 book 8 267 book 9 188 book 10 142 book 11 281 book 12 138 book 13 326 book 14 264 book 15 103 ^ number of pages What would be the best graph or display to represent …

More Similar Questions