Denise is trying to open a safe whose combination she does not know.
IF the safe has 4000 possible combinations,and she can try 75 different
possibilities,what is the probability that she does not pick the one
correct combination. Select
A) 1	B) 159 / 160	C) 157 / 160	D) 4 3 / 160	E) 0

Rationale: when trying the first time the probability denise does n ' t pick the correct combination = 3999 / 4000 second time , as the total number of possible combinations reduced by one , not picking the right one would be 3998 / 3999 . third time 3997 / 3998 . . . and the same 75 times . so we get : 3999 / 4000 ∗ 3998 / 3999 ∗ . . . ∗ 3925 / 39263999 / 4000 ∗ 3998 / 3999 ∗ . . . ∗ 3925 / 3926 every denominator but the first will cancel out and every nominator but the last will cancel out as well . we ' ll get 3925 / 4000 = 157 / 160 . answer : c .
Answer: C