∵x~B(3,13),
∴P(x=1)=C13(13)(1-13)2=49.
故答案为:49.
阅读下列短文,判断对错,分别用“√”和“×”表示。
I go to school from Monday to Friday. Every (每个) morning I get up at six thirty. I have breakfast at six
forty-five and then I go to school. I have four classes in the morning and two in the afternoon. I have lunch at
school. I go home at five thirty. I have dinner at home at six twenty. I watch TV in the evening. I go to bed at
ten forty.
( ) 1. I get up at 6: 30.
( ) 2. I have breakfast at school.
( ) 3. I have five classes every day.
( ) 4. I have lunch at home.
( ) 5. I go to bed at 10: 40.
下列4种设备中,属于计算机输入设备的是
A.LIPS
B.服务器
C.绘图仪
D.光笔