Use this decision tree for three questions. Assume the decision maker maximizes expected value. Recall that square nodes are such that the decision maker must choose between the options and circle nodes are such that nature randomly selects, according to the given probabilities, from the available options. tree.JPG

What is the expected value at node $4,$ assuming the decision maker acts optimally?

Group of answer choices

$$1600$

$$800$

None of these

$$700$

$$400$