有30张牌,牌面朝下,每次抽出一张记下花色再放回,洗牌后再抽,经历多次试验后,记录抽到红桃的频率为20%,则红桃大约有______张.
由题意可得,红桃大约有:30×20%=6张.
阅读下面对话,从方框内7个选项中选择5个恰当的句子完成此对话。
A: Hi, Jack! Will your school have a sports meeting this Friday?
B: 小题1:
A: You are going to take part in the 400-meter run, aren’t you?
B: Yes, mom.
A: I hope you will win. 小题2: Will they take part in the sports meeting?
B: 小题3: Tom is going to do the high jump. Jenny is good at the long jump, so she will take part in the long jump competition.
A: 小题4:
B: I practice it after school every day. But I feel a little nervous.
A: Don’t worry, Jack. Believe in yourself. You’re great!
B: 小题5:
电磁流量计由哪两部分组成?