The head chef A can cook one dish in 4 minutes.
His fellow chef B can finish in 8 minutes,
A young chef C has an unknown capability.
Then two more chefs are hired into the team.
Chef D can cook one dish in 6 minutes.
Chef E can cook one dish in 9 minutes.
If the average cooking time per person before and after the new hiring is unchanged, in how many minutes can chef C cook one dish?