SOLUTION: a person has 175 coins and he wants to arrange the coins in some rows and columns such that the number of columns is twice the number of rows .what is the minimum number of additi

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Question 815179: a person has 175 coins and he wants to arrange the coins in some rows and columns such that the number of columns is twice the number of rows .what is the minimum number of additional coins needed for such an arrangement
Answer by Edwin McCravy(20065) About Me  (Show Source):
You can put this solution on YOUR website!
Let the number of rows be x
Then the number of columns will be 2x
Then the number of coins will be (x)(2x)

Then (x)(2x) ≧ 175
         2x² ≧ 175
Divide both sides by 2:
          x² ≧ 87.5
Take positive square roots of both sides:
           x ≧ √87.5
           x ≧ 9.354143467S

So the smallest whole number x can be is 10

So there would be 10 rows and 20 columns.
That would be 10×20=200 coins.

So we'd need 200-175 or 25 more coins.  

Edwin