10.已知一组数据1、2、3、x、7的平均数为3,则这组数据的众数与中位数分别是( )
| A. | 3,3 | B. | 2,2 | C. | 2,3 | D. | 2,2.5 |
9.已知a-b=1,a+b=-3,则a2-ab=( )
| A. | -1 | B. | 1 | C. | -3 | D. | 3 |
7.某商店的老板销售一种商品,要以不低于进价120%的价格出售,但为了获得更多利润,以高出进价80%的价格标价.若你想买下标价为360元的这种商品,最多降价( )元时,商店老板才会将商品卖给你.
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| A. | 80 | B. | 100 | C. | 120 | D. | 160 |