How much time will (4,10,14,16,18) workers take to do the job?

In this problem, the number of workers working on a single project should be inversely proportional to the time needed to finish the project. In this case, the function should be f(x) = 1/2^X. Hence with x equal to {4, 10, 14, 16, 18}, then f(x) is equal to {0.1, 0.4, 0.6, 0.8, 0.9}