



 
Hi Keith, Look at my response to Toumas' question concerning a roll of paper. In it I showed that \[t \times L = \pi (R^2  r^2)\] where $t$ is the thickness pf the paper, $L$ is the length of the paper on the roll, $R$ is the radius of the roll and $r$ is the radius of the core. All the dimensions need to be in the same units so if we use millimeters then you have $L = 7,750,000$ mm. Use this formula to solve for $t.$ Write back if you need more help,  


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