1、正确答案是D
解析：由每分钟可录入4份，原计划90分钟可完成，可知总的份数为 4×90=360，假设破损a份，则
a=36份，破损率=36/360=10%。
2、正确答案是A
解析：第三次才中奖，说明前两次为不中奖情况，即抽出的球不是白色，第三次抽出的为白色，其概率= 
。
3、正确答案是B
解析：8个不同的自然数，任意4个数的乘积是偶数，则最多有3个奇数。全部8个数的和是奇数，则奇数的个数只能是1个或3个。
当奇数为1个时，8个数最小情况为：1、2、4、6、8、10、12、14；当奇数为3个时，8个数最小情况为：1、3、5、2、4、6、8、10。很明显当奇数为3个时，加和最小，最小和=1+3+5+2+4+6+8+10=39。
4、正确答案是A
解析：设商品成本为10，则可得：
打折后比打折前的利润减少了：(4-3.6)/4=10%。
5、正确答案是D
解析：30%和40%的溶液混合成35%的溶液，易得两溶液比应为1：1，即从甲烧杯中取出的溶液质量应为100g，则倒回的质量也应为100g，则甲烧杯中最终溶液的浓度为(100×35%+400×30%)/500=31%。
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