Bài tập cuối chương VI
<div data-v-a7c68f28=""><span data-v-a7c68f28="">Hướng dẫn giải Bài 5 (Trang 54 SGK Toán 10, Bộ Cánh diều, Tập 2)</span></div>
<p><strong>B&agrave;i 5 (Trang 54 SGK To&aacute;n 10, Bộ C&aacute;nh diều, Tập 2)</strong></p> <p>Em h&atilde;y t&igrave;m hiểu chiều cao của tất cả c&aacute;c bạn trong tổ v&agrave; lập mẫu số liệu với kết quả tăng dần. Với mẫu số liệu đ&oacute;, h&atilde;y t&igrave;m:</p> <p>a) Số trung b&igrave;nh cộng, trung vị v&agrave; tứ ph&acirc;n vị;</p> <p>b) Khoảng biến thi&ecirc;n v&agrave; khoảng tứ ph&acirc;n vị;</p> <p>c) Phương sai v&agrave; độ lệch chuẩn.</p> <p><em><span style="text-decoration: underline;"><strong>Hướng dẫn giải</strong></span></em></p> <p>V&iacute; dụ, ta c&oacute; bảng đo chiều cao của c&aacute;c bạn trong tổ như sau:</p> <p><img class="wscnph" style="max-width: 100%;" src="https://static.colearn.vn:8413/v1.0/upload/library/14112022/anh-chup-man-hinh-2022-11-14-085315-iDM0PF.png" width="530" height="50" /></p> <p>a) Sắp xếp mẫu số liệu theo thứ tự kh&ocirc;ng giảm ta được:</p> <p align="center">160&nbsp;&nbsp; 162&nbsp;&nbsp;&nbsp;&nbsp; 164&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 165&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 172&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 174&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 177&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 178&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 180</p> <p>Số trung b&igrave;nh cộng của mẫu số liệu tr&ecirc;n l&agrave;:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mover><mi>x</mi><mo>&macr;</mo></mover><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mfrac><mrow><mn>160</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>162</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>164</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>165</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>172</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>174</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>177</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>178</mn><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mn>180</mn></mrow><mn>9</mn></mfrac><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mfrac><mn>1532</mn><mn>9</mn></mfrac></math></p> <p>Trung vị của mẫu số liệu tr&ecirc;n l&agrave;: Do mẫu số liệu tr&ecirc;n c&oacute; 9 số liệu ( lẻ ) n&ecirc;n trung vị&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Q</mi><mn>2</mn></msub><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mn>172</mn></math></p> <p>Tứ ph&acirc;n vị của mẫu số liệu tr&ecirc;n l&agrave;:</p> <p>-&nbsp; Trung vị của d&atilde;y 160&nbsp;&nbsp; 162&nbsp; 164&nbsp;&nbsp; 165 l&agrave;:&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Q</mi><mn>1</mn></msub><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mn>163</mn></math></p> <p>- Trung vị của d&atilde;y&nbsp; 174&nbsp;&nbsp; 177&nbsp; 178&nbsp;&nbsp; 180 l&agrave;: <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Q</mi><mn>3</mn></msub><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mn>177</mn><mo>,</mo><mn>5</mn></math></p> <p>b) Khoảng biến thi&ecirc;n của mẫu số liệu tr&ecirc;n l&agrave;:&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>R</mi><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><msub><mi>x</mi><mrow><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>&nbsp;</mo><mo>-</mo><mo>&nbsp;</mo><msub><mi>x</mi><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mn>180</mn><mo>&nbsp;</mo><mo>-</mo><mo>&nbsp;</mo><mn>160</mn><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mn>20</mn></math></p> <p>Khoảng tứ ph&acirc;n vị của mẫu số liệu tr&ecirc;n l&agrave;:&nbsp;<span id="MathJax-Element-22-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: 400; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: 0px; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; color: #000000; font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-variant-ligatures: normal; font-variant-caps: normal; orphans: 2; widows: 2; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msub&gt;&lt;mi mathvariant=&quot;normal&quot;&gt;&amp;#x0394;&lt;/mi&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msub&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mo&gt;&amp;#x2212;&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msub&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;177&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;mo&gt;&amp;#x2212;&lt;/mo&gt;&lt;mn&gt;163&lt;/mn&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;14&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/math&gt;"><span id="MJXc-Node-438" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-439" class="mjx-mrow"><span id="MJXc-Node-440" class="mjx-texatom"><span id="MJXc-Node-441" class="mjx-mrow"><span id="MJXc-Node-442" class="mjx-msubsup"><span class="mjx-base"><span id="MJXc-Node-443" class="mjx-mi"></span></span></span></span></span></span></span></span><br /><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mo>∆</mo><mi>Q</mi></msub><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><msub><mi>Q</mi><mn>3</mn></msub><mo>&nbsp;</mo><mo>-</mo><mo>&nbsp;</mo><msub><mi>Q</mi><mn>1</mn></msub><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mn>177</mn><mo>,</mo><mn>5</mn><mo>&nbsp;</mo><mo>-</mo><mo>&nbsp;</mo><mn>163</mn><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mn>14</mn><mo>,</mo><mn>5</mn></math></p> <p>&nbsp;</p> <p>c) Phương sai của mẫu số liệu tr&ecirc;n l&agrave;:&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>s</mi><mn>2</mn></msup><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><mfrac><mrow><mo>[</mo><msup><mrow><mo>(</mo><mn>160</mn><mo>&nbsp;</mo><mo>-</mo><mo>&nbsp;</mo><mover><mi>x</mi><mo>&macr;</mo></mover><mo>)</mo></mrow><mn>2</mn></msup><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><msup><mrow><mo>(</mo><mn>162</mn><mo>&nbsp;</mo><mo>-</mo><mo>&nbsp;</mo><mover><mrow><mi>x</mi></mrow><mrow><mo>&macr;</mo></mrow></mover><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msup><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>&nbsp;</mo><mo>+</mo><mo>&nbsp;</mo><msup><mrow><mo>(</mo><mn>180</mn><mo>&nbsp;</mo><mo>-</mo><mo>&nbsp;</mo><mover><mi>x</mi><mo>&macr;</mo></mover><mo>)</mo></mrow><mn>2</mn></msup><mo>]</mo></mrow><mn>9</mn></mfrac><mo>&nbsp;</mo><mo>&asymp;</mo><mo>&nbsp;</mo><mn>50</mn><mo>&nbsp;</mo><mo>,</mo><mo>&nbsp;</mo><mn>84</mn></math></p> <p>Độ lệch chuẩn của mẫu số liệu tr&ecirc;n l&agrave;:&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>s</mi><mo>&nbsp;</mo><mo>=</mo><mo>&nbsp;</mo><msqrt><msup><mi>s</mi><mn>2</mn></msup></msqrt><mo>&nbsp;</mo><mo>&asymp;</mo><mo>&nbsp;</mo><mn>7</mn><mo>&nbsp;</mo><mo>,</mo><mo>&nbsp;</mo><mn>13</mn><mo>&nbsp;</mo><mo>&nbsp;</mo><mo>&nbsp;</mo></math></p> <p align="center"><span id="MathJax-Element-23-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 16.94px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msup&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msup&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mn&gt;160&lt;/mn&gt;&lt;mo&gt;&amp;#x2212;&lt;/mo&gt;&lt;mover&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo accent=&quot;false&quot;&gt;&amp;#x00AF;&lt;/mo&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msup&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mn&gt;162&lt;/mn&gt;&lt;mo&gt;&amp;#x2212;&lt;/mo&gt;&lt;mover&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo accent=&quot;false&quot;&gt;&amp;#x00AF;&lt;/mo&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msup&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mn&gt;180&lt;/mn&gt;&lt;mo&gt;&amp;#x2212;&lt;/mo&gt;&lt;mover&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo accent=&quot;false&quot;&gt;&amp;#x00AF;&lt;/mo&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mn&gt;9&lt;/mn&gt;&lt;/mfrac&gt;&lt;mo&gt;&amp;#x2248;&lt;/mo&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;84&lt;/mn&gt;&lt;/math&gt;"><span id="MJXc-Node-467" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-468" class="mjx-mrow"><span id="MJXc-Node-469" class="mjx-texatom"><span id="MJXc-Node-470" class="mjx-mrow"><span id="MJXc-Node-471" class="mjx-msubsup"><span class="mjx-base"><span id="MJXc-Node-472" class="mjx-mi"></span></span></span></span></span></span></span></span></p>
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