Three workers are digging a hole. They work one by one, and every single of them works exactly
the amount of time it would have taken the other two to complete the digging of the entire hole.
They finish digging the hole by taking one turn each. How many times faster would they have
digged the hole if they worked together?
(A) 2.5 (B) 3 (C) 3.5 (D) 4 (E) 5