Four investors provide capital on reason 1:2:3: 4 what is the arithmetic mean of 4 initial capital?

Four investors provide capital on reason 1:2:3: 4, achieving a total capital of U$ 360,000,000

1) a fifth investor wants to participate in the business with u$ 250.000.000, the four initial investors are in agreement, on condition that will keep the initial proportionality constant. What is the maximum contribution you can make the fifth investor society?

(2) what is the arithmetic mean of 4 initial capital?

(3) what is the minimum amount for the entry of a fifth investor, maintaining the constant of proportionality that the four initial investors form?