Aswimming pool can be filled in 16 hours if water enters through a pipe alone, or in 23 hours if water enters through a hose alone. if water is entering through both the pipe and the hose, how long will take to fill the pool

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?