Which monomial is a perfect cube? 16x627x832x1264x6

You were told that the amount of time lapsed between consecutive trades on the new york stock exchange followed a normal distribution with a mean of 15 seconds. you were also told that the probability that the time lapsed between two consecutive trades to fall between 16 to 17 seconds was 13%. the probability that the time lapsed between two consecutive trades would fall below 13 seconds was 7%. what is the probability that the time lapsed between two consecutive trades will be between 14 and 15 seconds?

Which representation has a constant of variation of -2.5

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?