Question

19£®½«µÈÎïÖʵÄÁ¿XºÍY¼ÓÈëÃܱÕÈÝÆ÷£¬ÔÚÒ»¶¨Ìõ¼þÏ·¢Éú·´Ó¦£ºX£¨g£©+Y£¨g£©?Z £¨s£©+2W£¨g£©£¬Æ½ºâʱWµÄÌå»ý·ÖÊý£¨%£©ËæζȺÍѹǿµÄ±ä»¯Èç±íËùʾ£®

	1.0 MPa	2.0 MPa	3.0 MPa
800¡æ	a	b	83%
900¡æ	c	75%	d
1000¡æ	54%	e	f

¢Ùa£¾c£¾f   ¢Ú900¡æ¡¢2.0MPaʱ£¬XµÄת»¯ÂÊΪ75%¡¡    ¢Û¸Ã·´Ó¦µÄ¡÷H£¼0      ¢Üƽºâ³£ÊýK£¨1000¡æ£©£¾K£¨800¡æ£©ÉÏÊö¢Ù¡«¢ÜÖÐÕýÈ·µÄÓУ¨¡¡¡¡£©

• A£® 4¸ö
• B£® 3¸ö
• C£® 2¸ö
• D£® 1¸ö

Answer 1

·ÖÎö ¢ÙX£¨g£©+Y£¨g£©?Z £¨s£©+2W£¨g£©£¬·´Ó¦Ç°ºóÆøÌå·Ö×ÓÊý²»±ä£¬¹ÊÏàͬζÈÏ£¬Ôö´ó²»Ó°ÏìƽºâÒƶ¯£¬¹Êa=b=83%£¬c=d=75%£¬e=f=54%£»
¢Ú900¡æʱX£¨g£©+Y£¨g£©?Z £¨s£©+2W£¨g£©£¬
      ¿ªÊ¼    n            n                            0
      ת»¯    x            x                            2x
       ƽºâ  n-x         n-x                          2x
Ôò$\frac{2x}{2n-2x+2x}$=75%£¬½âµÃx=$\frac{3}{4}$n£»
¢ÛÓɱí¸ñÊý¾Ý¿ÉÖª£¬Î¶ÈÔ½¸ß£¬Æ½ºâʱWµÄÌå»ý·ÖÊýԽС£»
¢Ü·ÅÈÈ·´Ó¦µÄζÈÔ½¸ß£¬KԽС£®

½â´ð ½â£º¢ÙX£¨g£©+Y£¨g£©?Z £¨s£©+2W£¨g£©£¬·´Ó¦Ç°ºóÆøÌå·Ö×ÓÊý²»±ä£¬¹ÊÏàͬζÈÏ£¬Ôö´ó²»Ó°ÏìƽºâÒƶ¯£¬¹Êa=b=83%£¬c=d=75%£¬e=f=54%£¬Ôòa£¾c£¾f£¬¹ÊÕýÈ·£»
¢Ú900¡æʱX£¨g£©+Y£¨g£©?Z £¨s£©+2W£¨g£©£¬
      ¿ªÊ¼    n            n                            0
      ת»¯    x            x                            2x
      Æ½ºâ  n-x         n-x                           2x
Ôò$\frac{2x}{2n-2x+2x}$=75%£¬½âµÃx=$\frac{3}{4}$n£¬Ôò900¡æ¡¢2.0MPaʱ£¬XµÄת»¯ÂÊΪ$\frac{\frac{3}{4}n}{n}$¡Á100%=75%£¬¹ÊÕýÈ·£»
¢ÛÓɱí¸ñÊý¾Ý¿ÉÖª£¬Î¶ÈÔ½¸ß£¬Æ½ºâʱWµÄÌå»ý·ÖÊýԽС£¬ÔòÉý¸ßζȣ¬Æ½ºâÄæÏòÒƶ¯£¬Õý·´Ó¦Îª·ÅÈÈ·´Ó¦£¬¼´¡÷H£¼0£¬¹ÊÕýÈ·£»
¢Ü·ÅÈÈ·´Ó¦µÄζÈÔ½¸ß£¬KԽС£¬Æ½ºâ³£ÊýK£¨1000¡æ£©£¼K£¨800¡æ£©£¬¹Ê´íÎó£»
¹ÊÑ¡B£®

µãÆÀ ±¾Ì⿼²é»¯Ñ§Æ½ºâµÄ¼ÆË㣬Ϊ¸ßƵ¿¼µã£¬°ÑÎÕƽºâÈý¶Î·¨¡¢×ª»¯ÂʵļÆË㼰ƽºâÒƶ¯µÄÓ°ÏìΪ½â´ðµÄ¹Ø¼ü£¬²àÖØ·ÖÎöÓë¼ÆËãÄÜÁ¦µÄ¿¼²é£¬×¢Òâѹǿ¸Ä±äʱ¸Ãƽºâ²»Òƶ¯£¬ÌâÄ¿ÄѶȲ»´ó£®