SOLUTION: A monument is constructed by laying a row of 35 bricks at ground level. A second row, with 5 fewer bricks is centered on that; a third row with 5fewer bricks is centered on the sec
Algebra ->
Sequences-and-series
-> SOLUTION: A monument is constructed by laying a row of 35 bricks at ground level. A second row, with 5 fewer bricks is centered on that; a third row with 5fewer bricks is centered on the sec
Log On
Question 841588: A monument is constructed by laying a row of 35 bricks at ground level. A second row, with 5 fewer bricks is centered on that; a third row with 5fewer bricks is centered on the second; and so on. The top row contains 10 bricks. How many bricks are there in the monument? Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! A monument is constructed by laying a row of 35 bricks at ground level. A second row, with 5 fewer bricks is centered on that; a third row with 5fewer bricks is centered on the second; and so on. The top row contains 10 bricks. How many bricks are there in the monument?
--------
You have an arithmetic series with a = 35 and d = -5
-----
Sum Formula::
S(n) = (n/2)(1st + last)
------
1st + last = 35+10
------
(35-10)/5 = 5 ;implies you subtracted 5 briks 5 times ;
therefore there are 6 rows
-----------
S(6) = (6/2)(45) = 3*45 = 135 bricks
================================
Cheers,
Stan H.
(