As the problem is worded, I assume, based on the context, that the question is about the area 
of the horizontal cross-section of the concrete wall, and not about the area of the wall itself.



With enough precision, the area of the horizontal cross-section is the product of the circumference 
by the wall thickness, both expressed in centimeters


    the area of the horizontal cross-section =  =  = 62857 cm^2.    ANSWER