Farmer Hank has fewer than 100 pigs on his farm. If he groups five to a pen, there are always three pigs left over. If he groups the pigs seven to a pen, there is always one left over. However, if he groups the pigs three to a pen, there no pigs left. What is the greatest number of pigs that Farmer Hank could have on his farm?

Mathematics · High School · Mon Jan 18 2021

Answered on

Here, we have to find the common multiple first, 

(5a+3) (Remainder = 3):      8  13  18   23  ...   78   83   88   93   98

 (7b+1) (Remainder = 1):       8  15  22  29  ...    78   85   92   99

(3c +0) (Remainder = 0):  3  6  9  12  15  ...  78  81  84  87  90  93  96  99  [fewer than 100]

The largest number (but less than 100) in all three lists is 78.

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