Five charges, q each are placed at the corners of regular pentagon of side a as shown in the figure.
How would your answer be affected, if pentagon is replaced by n-sided regular polygon with charged q at each of its corners ?

Explanation

When pentagon is replaced by n-sided regular polygon with charge q at each of its corners , the electric field at O would continue to be zero as symmetricity of the charges is due to the regularity of the polygon. It does not depend on the number of sides or the number of charges.