If 5 pencils and 2 eraser cost $0.90 andar the same price 3 pencils and 1 erasers cost $0.50 what is the cost of one pencils

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?