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Average of first, third digit mean middle digit

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November 14, 2005
calculusintegration

Problem Statement

How many three-digit numbers satisfy the property that the middle digit is the average of the first and the last digits? <spanclass=′latex−bold′>(A)</span> 41<spanclass=′latex−bold′>(B)</span> 42<spanclass=′latex−bold′>(C)</span> 43<spanclass=′latex−bold′>(D)</span> 44<spanclass=′latex−bold′>(E)</span> 45 <span class='latex-bold'>(A)</span>\ 41\qquad <span class='latex-bold'>(B)</span>\ 42\qquad <span class='latex-bold'>(C)</span>\ 43\qquad <span class='latex-bold'>(D)</span>\ 44\qquad <span class='latex-bold'>(E)</span>\ 45
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