Suppose that 10 people live on a street and that each of them is willing to pay $2 for each extra streetlight, regardless of the number of...

Suppose that 10 people live on a street and that each of them is willing to pay $2 for each extra streetlight, regardless of the number of streetlights provided. If the cost of providing g streetlights is given by    c(g)=g^2         , what is the Pareto efficient(optimal) number of streetlights to provide? (Hint: marginal cost of streetlight is  2g  ).