解题思路:根据题意
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为四位十进制纯小数,ai(i=1,2,3)只取0或1,故可以找出这些小数,然后求和.
这些小数一共有八个:0.1111,0.1101,0.1011,0.0111,0.1001,0.0101,0.0011,0.0001,
它们的和为:0.4448 所以t=8,s=0.4448,
[S/T]=[0.4448/8]=0.0556.
故答案为:0.0556.
点评:
本题考点: 数的十进制.
考点点评: 本题主要考查整数的十进制表示法,找出这些四位小数是解答的关键.