Question

令a=

11×65+13×66+15×67+17×68+19×69+21×70+23×71

11×64+13×65+15×66+17×67+19×68+21×69+23×70

．若将a化成小数，则a的百分位数字是

1

．

Answer 1

分析：根据题意，先把a化简，然后根据分数的估算求解即可．

解答：解：a=

11×65+13×66+15×67+17×68+19×69+21×70+23×71

11×64+13×65+15×66+17×67+19×68+21×69+23×70

=

11×64+13×65+15×66+17×67+19×68+21×69+23×70+11+13+15+17+19+21+23

11×64+13×65+15×66+17×67+19×68+21×69+23×70

=1+

11+13+15+17+19+21+23

11×64+13×65+15×66+17×67+19×68+21×69+23×70

所以，1+

11+13+15+17+19+21+23

(11+13+15+17+19+21+23)×70

＜a＜1+

11+13+15+17+19+21+23

(11+13+15+17+19+21+23)×64

所以，1+

1

70

＜a＜1+

1

64

，即：1.0143＜a＜1.0157．
所以a的百分位数字是1．
故答案为：1

点评：本题主要考查的分数的估算，根据题意找出方法，进行计算即可．