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Question
CBSEENMA8003486

Diameter of cylinder A is 7 cm,  and the height is 14 cm. Diameter of cylinder B is 14 cm and height  is 7 cm. Without doing any calculations can you suggest whose volume is greater? Verify it by finding the volume of both the cylinders. Check whether the cylinder with greater volume also has greater surface area?


Solution

In volume of a cylinder, the radius is multiplied by squaring it.
∴  Volume of cylinder B will be more than that of A.
Volume of cylinder A
                       Radius (r) = 7 over 2 space cm comma       Height (h) = 14 cm
∴   Volume of a cylinder A = πr squared straight h

                                       space space equals space 22 over 7 cross times open parentheses 7 over 2 close parentheses squared cross times 14 space cm cubed
                                   space space space space space space equals space 22 over 7 cross times 7 over 2 cross times 7 over 2 cross times 14 space cm cubed
                                 space space space space space space space space equals space 11 cross times 7 cross times 7 space cm cubed
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#4 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php(59): com_wiris_plugin_impl_RenderImpl->computeDigest(NULL, Array)
#5 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/service.php(19): com_wiris_plugin_impl_TextServiceImpl->service('mathml2accessib...', Array)
#6 {main}</pre>
Volume of cylinder B
                           Radius (r) = 14 over 2 equals 7 space cm
                           Height (h) = 7 cm
∴          Volume of the cylinder straight B equals space πr squared straight h
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#2 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/FolderTreeStorageAndCache.class.php(110): com_wiris_util_sys_Store->mkdirs()
#3 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/RenderImpl.class.php(231): com_wiris_plugin_impl_FolderTreeStorageAndCache->codeDigest('mml=<math xmlns...')
#4 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php(59): com_wiris_plugin_impl_RenderImpl->computeDigest(NULL, Array)
#5 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/service.php(19): com_wiris_plugin_impl_TextServiceImpl->service('mathml2accessib...', Array)
#6 {main}</pre>
                                                     equals space 22 over 7 cross times 7 cross times 7 cross times 7 space cm cubed
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#2 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/FolderTreeStorageAndCache.class.php(110): com_wiris_util_sys_Store->mkdirs()
#3 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/RenderImpl.class.php(231): com_wiris_plugin_impl_FolderTreeStorageAndCache->codeDigest('mml=<math xmlns...')
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#5 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/service.php(19): com_wiris_plugin_impl_TextServiceImpl->service('mathml2accessib...', Array)
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#4 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php(59): com_wiris_plugin_impl_RenderImpl->computeDigest(NULL, Array)
#5 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/service.php(19): com_wiris_plugin_impl_TextServiceImpl->service('mathml2accessib...', Array)
#6 {main}</pre>
Thus, cylinder B has greater volume.
Now,  
     Surface area of cylinder A = 2 space cross times space straight pi space cross times space straight r space cross times space left parenthesis straight r plus straight h right parenthesis
                                              =  space space space space 2 cross times 22 over 7 cross times 7 over 2 cross times open square brackets 7 over 2 plus 14 close square brackets space cm squared
                                              space equals space 11 cross times 35 over 2 space cm squared space equals space 11 space cross times space 35 space cm squared
                                              equals space 385 space cm squared
Surface area of cylinder B = 2 πrh left parenthesis straight r plus straight h right parenthesis space equals space 2 cross times 22 over 7 cross times 7 cross times left square bracket 7 plus 7 right square bracket space cm squared
                                                   space space equals space 2 cross times 22 cross times left square bracket 14 right square bracket space cm squared
                                                      space space equals space 616 space cm squared
Thus, the cylinder of greater capacity has greater (more) surface area.