Question

（6分）某區(qū)為了解全區(qū)2800名九年級(jí)學(xué)生英語(yǔ)口語(yǔ)考試成績(jī)的情況，從中隨機(jī)抽取了部分學(xué)生的成績(jī)（滿分24分，得分均為整數(shù)），制成下表：

分?jǐn)?shù)段（x分）	x≤16	17≤x≤18	19≤x≤20	21≤x≤22	23≤x≤24
人    數(shù)	10	15	35	112	128

1.（1）填空：

①本次抽樣調(diào)查共抽取了  ▲  名學(xué)生；

②學(xué)生成績(jī)的中位數(shù)落在  ▲  分?jǐn)?shù)段；

③若用扇形統(tǒng)計(jì)圖表示統(tǒng)計(jì)結(jié)果，則分?jǐn)?shù)段為x≤16的人數(shù)所對(duì)應(yīng)扇形的圓心角為  ▲  °；

2.（2）如果將21分以上（含21分）定為優(yōu)秀，請(qǐng)估計(jì)該區(qū)九年級(jí)考生成績(jī)?yōu)閮?yōu)秀的人數(shù)．

 

Answer 1

【答案】

 

1.（1）①300················································································································· 1分

②21≤x≤22·········································································································· 3分

③12······················································································································ 4分

 

2.2）2800×=2240（人）      5分

【解析】略