Three hundred students attended dedication cerimony of a new building on a college campus. THe president of the traditionally female college announced a new expansion program, which included plans to make the college coeducational. The number of students who learned of the new program 't' hr later is given by the function:

f(t) = 3000 / 1+Be^-kt

If 600 students on campus had heard about the new program in 2 hr after the ceremony, how many students had heard about the policy after 4 hrs?