Conjugacy Class Problem

playa007

1. The problem statement, all variables and given/known data
If a group has order 20 has 4 conjugacy classes, it must have a trivial centre. True or False?

2. Relevant equations
The Class Equation

3. The attempt at a solution
I believed the answer to be false with this following counterexample:
20 = lZ(G)l + (20/4 + 20/4 + 20/5 + 20/5) => order of Z(G) = 2 => the centre is non-trivial.
where 5, 5, 4, 4 is the size of the 4 conjugate classes respectively

Any feedback on my reasoning and any flaws are very much appreciated

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morphism

Homework Helper
You haven't demonstrated that such a group exists.

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