圈一圈,算一算。
圈一圈____
12-8=____
15-8=____
(Ⅰ)求a的值,并根据频率分布直方图,估计红包金额的众数;
(Ⅱ)以频率分布直方图中的频率作为概率,若甲、乙、丙三人从中各抢到一个红包,其中金额在1,2)的红包个数为X,求X的分布列和期望.
下列语句中,划线词语使用不正确的一项是( )
如图,在直角坐标系中有一个格点三角形ABC(顶点都在格点上的三角形),已知A(﹣2,1),B(﹣3,4),C(﹣4,1),直线MN过点M(2,5),N(5,2).
I'm Lucy. I have a happy family. There are four people in my family. My birthday is on January 1st. It's New Year's Day, too. My family and I will have a big dinner on that day. I have a little brother. He is four years old. His birthday is in winter. It's very cold but we can make a snowman. My mother's birthday is in March. My father's birthday is in March,too. We can plant trees and fly kites.