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Subj:.....Next Number IV (S608)
          by Philip J. Carter and Kenneth A. Russell 
          From the book "IQ Test" on 7/27/2008 
             Published by Sterling Pub. Co., Inc., 2008 
             387 Park Avenue South, New York, N.Y. 10016 
             Test #4, Problem #30, Page 79 

 What number should replace the question marks? 
 7,  17,  8 1/2,  14 1/4,  10,  11 1/2,  and  ??? 
 
 
 
 
 
 

                THE SOLUTION

11 1/2.

There are two series.
Adding 1 1/2 creates  7,  8 1/2,  10,  and the new number  11 1/2,
and subtracting 2 3/4 creates  17,  14 1/4,  and  11 1/2.

Jack, thank you for spotting the error I made typing this problem.
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