<P>이현녀 선생님의 답글입니다.</P> <P> </P> <P><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">1.서로 값이 다른 세 변량 a,b,c의 평균이 7이고</SPAN><FONT color=#0000ff> </FONT><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">a,b,c 중에서 서로 다른 두 변량의 곱에 대한 평균이 46일때,</SPAN><FONT color=#0000ff> </FONT><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">세 변량 a,b,c 의 표준편차를 구하면?</SPAN><FONT color=#0000ff> </FONT></P> <P> </P> <P><FONT color=#0000ff> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=259 align=absMiddle height=35><PARAM NAME="_cx" VALUE="6852"><PARAM NAME="_cy" VALUE="926"><PARAM NAME="BackColor" VALUE="3932222"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/57.2`8.2/12,[1]{{a`plus`b`plus`c}/{3}`equal`7 , {ab`plus`bc`plus`ca}/{3}`equal`46}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT></FONT> 이고, 이를 정리하면</P> <P> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=250 align=absMiddle height=18><PARAM NAME="_cx" VALUE="6614"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="4063280"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/56.2`4.3/12,[1]{a`plus`b`plus`c`equal`21, ab`plus`bc`plus`ca`equal`138}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT></P> <P>세 변량 <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=55 align=absMiddle height=18><PARAM NAME="_cx" VALUE="1455"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="3932222"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/12.6`4.3/12,[1]{a, b, c}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT>의 표준편차를 식으로 나타내어 정리하면</P> <P> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=426 align=absMiddle height=182><PARAM NAME="_cx" VALUE="11271"><PARAM NAME="_cy" VALUE="4815"><PARAM NAME="BackColor" VALUE="3932222"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/95.9`41.4/12,[1]{{{sigma`equal`sqrt{{{(a-7)}^{2}`plus`{(b-7)}^{2}`plus`{(c-7)}^{2}}/{3}}}#{equal` `sqrt{{{a}^{2}`plus`{b}^{2}`plus`{c}^{2}-14(a`plus`b`plus`c)`plus`49`times`3}/{3}}}#{equal` `sqrt{{{(a`plus`b`plus`c)}^{2}-2(ab`plus`bc`plus`ca)-14(a`plus`b`plus`c)`plus`49`times`3}/{3}}}#{equal` `sqrt{{{21}^{2}-2`times`138-14`times`21`plus`49`times`3}/{3}}`equal`sqrt{6}}}}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT></P> <P><A hideFocus style="selector-dummy: true" name="[문서의 처음]"></A></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">2.어느 대학교의 수학과의 모집 정원 20명에 대하여</SPAN> </P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">모두 100명이 지원하였다</SPAN> </P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">시험 후 합격선의 점수는 수험생 전체 평균보다 12점이 높고,</SPAN> </P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">합격자의 평균 보다 20점이 낮으며,불합격자의 평균의 2배보다</SPAN> </P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">70점이 낮을때 합격선의 점수는?</SPAN> </P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><SPAN style="TEXT-ALIGN: justify; LINE-HEIGHT: 21px; FONT-FAMILY: '바탕'; LETTER-SPACING: 0px; COLOR: #000000; FONT-SIZE: 10pt">①100점 ②110점 ③120점 ④130점 ⑤140점</SPAN> </P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"> </P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><FONT face=새굴림>합격생 : 20명 : 평균 m</FONT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><FONT face=새굴림>불합격생 : 80명 : 평균 n 라고 할 때</FONT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><FONT face=새굴림>전체 : 100명 : 평균 <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=156 align=absMiddle height=35><PARAM NAME="_cx" VALUE="4127"><PARAM NAME="_cy" VALUE="926"><PARAM NAME="BackColor" VALUE="4063280"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/34.9`8.2/12,[1]{{20m`plus`80n}/{100}`equal`{m`plus`4n}/{5}}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT></FONT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><FONT face=새굴림>합격선 <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=123 align=absMiddle height=35><PARAM NAME="_cx" VALUE="3254"><PARAM NAME="_cy" VALUE="926"><PARAM NAME="BackColor" VALUE="4063280"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/27.1`8.2/12,[1]{a`equal`{m`plus`4n}/{5}`plus`12}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT> ---- (1) </FONT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><FONT face=새굴림> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=84 align=absMiddle height=18><PARAM NAME="_cx" VALUE="2222"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="3932222"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/19.1`4.3/12,[1]{a `equal`m-20}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT> ----------(2)</FONT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><FONT face=새굴림> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=89 align=absMiddle height=18><PARAM NAME="_cx" VALUE="2354"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="3932222"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/20.3`4.3/12,[1]{a `equal`2n-70}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT> ----------(3) </FONT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"><FONT face=새굴림>(2), (3) 식을 <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=12 align=absMiddle height=18><PARAM NAME="_cx" VALUE="317"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="3932222"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/2.8`4.3/12,[1]{a}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT>에 관한 식으로 정리하여 (1) 식에 5를 곱하고 대입하여 풀면</FONT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=129 align=absMiddle height=18><PARAM NAME="_cx" VALUE="3413"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="4063280"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/29.1`4.3/12,[1]{5a `equal`m`plus`4n`plus`60}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=206 align=absMiddle height=18><PARAM NAME="_cx" VALUE="5450"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="4063280"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/47`4.3/12,[1]{5a `equal`a`plus`20`plus`2(a`plus`70)`plus`60}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT></P> <P style="TEXT-ALIGN: justify; LINE-HEIGHT: 160%; TEXT-INDENT: 0px; MARGIN: 0px; FONT-FAMILY: '바탕'; COLOR: #000000; FONT-SIZE: 10pt"> <OBJECT class=MATH classid=clsid:70E4BF88-2729-4A46-8794-D459BAC0EB63 width=61 align=absMiddle height=18><PARAM NAME="_cx" VALUE="1613"><PARAM NAME="_cy" VALUE="476"><PARAM NAME="BackColor" VALUE="3932222"><PARAM NAME="Enabled" VALUE="-1"><PARAM NAME="Script" VALUE="[0]#wh4/14.2`4.3/12,[1]{a `equal`110}/{#xc333333}"><PARAM NAME="FontSize" VALUE="12"><PARAM NAME="FontColor" VALUE="3355443"><PARAM NAME="Editable" VALUE="0"><PARAM NAME="Measurable" VALUE="0"></OBJECT></P>
