Question

7£®Ä³Ð£¸ßÒ»Ä꼶Óмס¢ÒÒ¡¢±ûÈýλѧÉú£¬ËûÃǵÚÒ»´Î¡¢µÚ¶þ´Î¡¢µÚÈý´ÎÔ¿¼µÄÎïÀí³É¼¨Èç±í£º

	µÚÒ»´ÎÔ¿¼ÎïÀí³É¼¨	µÚ¶þ´ÎÔ¿¼ÎïÀí³É¼¨	µÚÈý´ÎÔ¿¼ÎïÀí³É¼¨
ѧÉú¼×	80	85	90
ѧÉúÒÒ	81	83	85
ѧÉú±û	90	86	82

ÔòÏÂÁнáÂÛÕýÈ·µÄÊÇ£¨¡¡¡¡£©

• A£® ¼×¡¢ÒÒ¡¢±ûµÚÈý´ÎÔ¿¼ÎïÀí³É¼¨µÄƽ¾ùÊýΪ86
• B£® ÔÚÕâÈý´ÎÔ¿¼ÎïÀí³É¼¨ÖУ¬¼×µÄ³É¼¨Æ½¾ù·Ö×î¸ß
• C£® ÔÚÕâÈý´ÎÔ¿¼ÎïÀí³É¼¨ÖУ¬Òҵijɼ¨×îÎȶ¨
• D£® ÔÚÕâÈý´ÎÔ¿¼ÎïÀí³É¼¨ÖУ¬±ûµÄ³É¼¨·½²î×î´ó

Answer 1

·ÖÎö ·Ö±ðÇó³öƽÊý¡¢·½²î£¬ÓÉ´ËÄÜÇó³ö½á¹û£®

½â´ð ½â£ºÔÚAÖУ¬¼×¡¢ÒÒ¡¢±ûµÚÈý´ÎÔ¿¼ÎïÀí³É¼¨µÄƽ¾ùÊýΪ$\overline{x}$=$\frac{1}{3}£¨90+85+82£©$¡Ö85.7£¬¹ÊA´íÎó£»
ÔÚBÖУ¬$\overline{{x}_{¼×}}$=$\frac{1}{3}£¨80+85+90£©$=85£¬$\overline{{x}_{ÒÒ}}$=$\frac{1}{3}$£¨81+83+85£©=83£¬$\overline{{x}_{±û}}$=$\frac{1}{3}£¨90+86+82£©$=86£¬
¡àÔÚÕâÈý´ÎÔ¿¼ÎïÀí³É¼¨ÖУ¬±ûµÄ³É¼¨Æ½¾ù·Ö×î¸ß£¬¹ÊB´íÎó£»
ÔÚCÖУ¬${{S}_{¼×}}^{2}$=$\frac{1}{3}[£¨80-85£©^{2}+£¨85-85£©^{2}+£¨90-85£©^{2}]$=$\frac{50}{3}$£¬
${{S}_{ÒÒ}}^{2}$=$\frac{1}{3}$[£¨81-83£©²+£¨83-83£©²+£¨85-83£©²]=$\frac{8}{3}$£¬
${{S}_{±û}}^{2}$=$\frac{1}{3}$[£¨90-86£©²+£¨86-86£©²+£¨82-86£©²]=$\frac{32}{3}$£¬
¡àÔÚÕâÈý´ÎÔ¿¼ÎïÀí³É¼¨ÖУ¬Òҵijɼ¨×îÎȶ¨£¬¹ÊCÕýÈ·£»
ÔÚDÖУ¬ÔÚÕâÈý´ÎÔ¿¼ÎïÀí³É¼¨ÖУ¬¼×µÄ³É¼¨·½²î×î´ó£¬¹ÊD´íÎó£®
¹ÊÑ¡£ºD£®

µãÆÀ ±¾Ì⿼²éƽ¾ùÊý¡¢·½²îµÄÇ󷨼°Ó¦Ó㬿¼²éÊý¾Ý´¦ÀíÄÜÁ¦¡¢ÔËËãÇó½âÄÜÁ¦£¬¿¼²éº¯ÊýÓë·½³Ì˼Ï룬ÊÇ»ù´¡Ì⣮