In an Experiment to Test the Effectiveness of the Latest

Multiple Choice

In an experiment to test the effectiveness of the latest roach trap, the "Roach Resort"; 70 roaches were placed in the vicinity of the trap and left there for an hour. At the end of the hour, it was observed that 42 of them had "checked in" while the rest were still scurrying around. (Remember that "once a roach checks in, it never checks out.") If a roach begins outside the "Resort", what is the probability of it "checking in" by the end of 3 hours ?

A) 0.4
B) 1
C) 0.36
D) 0.936
E) 0.216