A school chorus has 90 sixth-grade students and 75 seventh-grade students. The music director wants to make groups of performers, with the same combination of sixth- and seventh-grade students in each group. She wants to form as many groups as possible. What is the largest number of groups that could be formed? Explain or show your reasoning. If that many groups are formed, how many students of each grade level would be in each group?

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?