Math
posted by Anonymous .
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
Respond to this Question
Similar Questions

Math
Julia wants to build another garden wall, 10 bricks long and 3 bricks high. Can she build it with red and white bricks, so that no two bricks of the same color are next to each other? 
maths
A brick wall is built by using 2 bricks less in each layer than in the previous one. The wall has m layers and in total 21m+40 bricks are used. If the top layer has only 4 bricks, determine:A) the value of m b) the total number of … 
Algebra
A brick staircase has a total of 16 steps The bottom step requires 112 bricks. Each successive step requires 4 fewer bricks than the prior one. How many bricks are required to build the staircase? 
Math
Mike bought 252 bricks to build a wall in his yard. Each row has 14 bricks. Each bricks is 3 inches tall. How many inches tall will be wall be if Mike uses every brick? 
MATH
a pile of bricks has 85 bricks in the bottom row, 79 bricks in the second row, 73 in the third row, and so on until there is only 1 brick in the top row. how many bricks are in the 12th row? 
math
bricks are stacked in 20 rows such that each row has a fixed number of bricks more than the row above it. the top row has 5 bricks and the bottom row 62 bricks. how many bricks are in the stack? 
math
Task is to construct two brick columns of the dimensions shown on which an iron gate will eventually be hung. Because the bricks measure 8" long by 3 1/2" wide by 2 1/2" high, you decide to build each column by laying the bottom row … 
Physics
Four bricks are to be stacked at the edge of a table, each brick overhanging the one below it, so that the top brick extends as far as possible beyond the edge of the table. *The construction in stable equilibrium, bricks must extend … 
college algebra help******
Sequences 1. Constructing a Brick Staircase A brick staircase has a total of 30 steps. The bottom step requires 100 bricks. Each successive step requires two less bricks than the prior step. a. How many bricks are required for the … 
Math
Building Bricks A child is playing with building bricks like this one. He decides to build the simple tower shown. How many bricks would he need to build this tower?