people were polled on how many books they read the previous

Solution

Note that      
      
n = z(alpha/2)^2 s^2 / E^2      
      
where      
      
alpha/2 = (1 - confidence level)/2 =    0.005  
      
Using a table/technology,      
      
z(alpha/2) =    2.575829304  
      
Also,      
      
s = sample standard deviation =    10.1  
E = margin of error =    1  
      
Thus,      
      
n =    676.8258023  
      
Rounding up,      
      
n =    677   [answer]