SOLUTION: Can someone please walk me through this? Plastic pipe is stacked so that the bottom row has 25 pipes, the next row has 24 pipes, the next row has 23 pipes, and so on until there

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Can someone please walk me through this? Plastic pipe is stacked so that the bottom row has 25 pipes, the next row has 24 pipes, the next row has 23 pipes, and so on until there      Log On


   

Question 330237: Can someone please walk me through this?
Plastic pipe is stacked so that the bottom row has 25 pipes, the next row has 24 pipes, the next row has 23 pipes, and so on until there is 1 pipe at the top of the stack. If a worker removes the top 17 rows of pipe, how many pieces of pipe will be left in the stack?
___ pieces of pipe
Thank you,
Edgar
Found 3 solutions by Fombitz, solver91311, stanbon:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
You have 25 rows of pipe.
17 rows are removed which leaves rows 18 through 25.
P=18%2B19%2B20%2B21%2B22%2B23%2B24%2B25
P=172 pieces of pipe

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


The sum of a series of numbers is equal to the sum of the first number and the last number multiplied by the number of numbers and the product divided by 2.

For your problem, if they removed the first 17 rows of pipe, the first number in your series becomes 18. The last is 24.



You can do your own arithmetic -- and you should be able to do it in your head.

John

My calculator said it, I believe it, that settles it

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Can someone please walk me through this?
Plastic pipe is stacked so that the bottom row has 25 pipes, the next row has 24 pipes, the next row has 23 pipes, and so on until there is 1 pipe at the top of the stack. If a worker removes the top 17 rows of pipe, how many pieces of pipe will be left in the stack?
___ pieces of pipe
--------------------
The total number of pipes is 1+2+3+...+23+24+25
= (25/2)(1+25) = 325
-------------------------
The top 17 rows have 1+2+3+4...+15+16+17
= (17/2)(1+17) = 153
-----------------------------
You can figure out how many are left after removing 153 of the pipes.
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Cheers,
Stan H.
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