问题 填空题
0.
.
a1a2a31
为四位十进制纯小数,ai(i=1,2,3)只取0或1.记T是所有这些四位小数的个数,S是所有这些四位小数的和,则
S
T
=______.
答案

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.

单项选择题
单项选择题