Ihad to find what the input would be for f(x)=x2-1 if the output was 99. so then i did x2-1=99 and added 1 on each side so i'm left with x2=100. what do i do now?

Find the number of positive three-digit even integers whose digits are among 9, 8, 7,5, 3, and 1.

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?

10% of 1,900,000. show me how you got the answer