题目

If asked if space exploration should continue, most Americans would give an immediate response either in favor of continuing or in favor of ending space exploration. A common response would be that space exploration is a waste of money. An average American, uneducated on the subject, might believe that the government is wasting billions of dollars on the research that has no merit. Someone strange to the subject might say that a space shuttle goes up once in a while and that is about all that happens. Research is ongoing and continues when there are no shuttles being launched. This als某班50名学生在一次百米测试中，成绩全部介于13秒与19秒之间，将测试结果按如下方式分成六组：每一组，成绩大于等于13秒且小于14秒；第二组，成绩大于等于14秒且小于15秒；…第六组，成绩大于等于18秒且小于等于19秒．如图是按上述分组方法得到的频率分布直方图．设成绩小于17秒的学生人数占全班人数的百分比为x，成绩大于等于15秒且小于17秒的学生人数为y，则从频率分布直方图中可以分析出x和y分别为（ ）A．0.9，35B．0.9，45C．0.1，35D．0.1，45