Posted by **Anonymous** on Monday, December 27, 2010 at 10:17am.

A pile of bricks has 85 bricks in the bottom row, 81 bricks in the second row up, 77 in the third, and so on up to the top row that contains only 1 brick. How many bricks are in the 12th row?

I don't know if I'm right but I attempted this problem below

c = a1 - d

c = 85 - 4 = 81

- 85 + 81 = 166

Sn = n / 2 (a1 + an)

Sn = 85 / 2 (85 + 166)

Sn = 10667.5

- Math -
**Dr Russ**, Monday, December 27, 2010 at 10:30am
I can't follow you calculation.

Row 1 has

85

Row 2 has

81

row 3 has

77

The nth row will have

85-4(n-1)

so if n=12

then

85-4(12-1)=85-44=41 bricks

- Math -
**Anonymous**, Monday, December 27, 2010 at 10:42am
Right, instead of using the Sn formula. I could have just use an = a1 + (n - 1) d

Thanks a lot

## Answer this Question

## Related Questions

- MATH - a pile of bricks has 85 bricks in the bottom row, 79 bricks in the second...
- math - bricks are stacked in 20 rows such that each row has a fixed number of ...
- math - Task is to construct two brick columns of the dimensions shown on which ...
- Math - Mike bought 252 bricks to build a wall in his yard. Each row has 14 ...
- maths - A brick wall is built by using 2 bricks less in each layer than in the ...
- Math - Julia wants to build another garden wall, 10 bricks long and 3 bricks ...
- Advanced Math - Find DE if matrix D= Row 1= -2,4,6 and ROW 2= 5,-7,1 and matrix ...
- math - A gardener is making a triangular planting, with 35 plants in the front ...
- math - a gardener is making a triangle planting with 35 plants in row ,31 in the...
- Math - A patio was to be laid in a design with one tile in the first row,two ...