Question

（6分）某區(qū)為了解全區(qū)2800名九年級(jí)學(xué)生英語口語考試成績的情況，從中隨機(jī)抽取了部分學(xué)生的成績（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

【小題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  ▲ °；
【小題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?yōu)閮?yōu)秀的人數(shù)．

Answer 1

【小題1】（1）①300················································································· 1分
②21≤x≤22···················································································· 3分
③12······························································································ 4分
【小題2】2）2800×=2240（人）    5分解析:
略