SOLUTION: A 12-wheeler truck is loaded with 13 piles of log. The bottom row contains 25 logs. Each of the remaining piles contains 2 logs less than the number of logs on a pile directly belo
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-> SOLUTION: A 12-wheeler truck is loaded with 13 piles of log. The bottom row contains 25 logs. Each of the remaining piles contains 2 logs less than the number of logs on a pile directly belo
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Question 1169266: A 12-wheeler truck is loaded with 13 piles of log. The bottom row contains 25 logs. Each of the remaining piles contains 2 logs less than the number of logs on a pile directly below it. Find the total weight of the logs carried by the truck if each log weighs 57kg.
I hope you can help me to solve this. I’ve already watched a lot of youtube videos but I still don’t get it :( Thank you so much! Answer by ikleyn(52788) (Show Source):
You have two ways.
First way is to notice that the numbers are
25 logs (1-st, bottom pile)
23 logs (2-nd, next pile)
21 logs (3-rd pile)
19 logs
. . . . .
25-2*(13-1) = 25-2*12 = 25-24 = 1 log (13-th pile)
Then to add the numbers 25 + 23 + 21 + 19 + . . . + 1 manually or using your calculator.
For it, there is no need to watch YouTube videos, at all.
But if you know what an arithmetic progression is, you may apply formulas for summing its terms.
You have 13 terms; the first term is = 25; the last, 13-th term is = 1.
Hence, the sum of the thirteen terms is = = = = 13*13 = 169.
The last step is to multiply 57 kilograms by 169.
