{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2026-05-26T00:16:20.000Z","description":"Problems submitted by members of the MATLAB Central community.","is_default":true,"created_by":161519,"badge_id":null,"featured":false,"trending":false,"solution_count_in_trending_period":0,"trending_last_calculated":"2026-05-26T00:00:00.000Z","image_id":null,"published":true,"community_created":false,"status_id":2,"is_default_group_for_player":false,"deleted_by":null,"deleted_at":null,"restored_by":null,"restored_at":null,"description_opc":null,"description_html":null,"published_at":null},"problems":[{"id":281,"title":"Acid and water","description":"\u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878;\r\n\r\nAssume that there is a 100 liter tank. \r\n\r\nIt is initially filled with just distilled water. \r\n\r\nIt is continuously drained at R liters per minute. \r\n\r\nThis tank is always maintained full and homogeneous by continuously adding and stirring R liters per minute of an unknown acid (or some fancy oil if it helps you solving this problem). \r\n\r\nHow many liters W of water will be in the tank after M minutes?\r\n\r\nNeglect any expansion or contraction when the acid is mixed with water. ","description_html":"\u003cp\u003e\u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878;\u003c/p\u003e\u003cp\u003eAssume that there is a 100 liter tank.\u003c/p\u003e\u003cp\u003eIt is initially filled with just distilled water.\u003c/p\u003e\u003cp\u003eIt is continuously drained at R liters per minute.\u003c/p\u003e\u003cp\u003eThis tank is always maintained full and homogeneous by continuously adding and stirring R liters per minute of an unknown acid (or some fancy oil if it helps you solving this problem).\u003c/p\u003e\u003cp\u003eHow many liters W of water will be in the tank after M minutes?\u003c/p\u003e\u003cp\u003eNeglect any expansion or contraction when the acid is mixed with water.\u003c/p\u003e","function_template":"function W = tank(R,M)\r\n  W = 100 * R * M;\r\nend","test_suite":"%%\r\nR=1; \r\nM=1;\r\nW=99;\r\nassert(tank(R,M)\u003eW)\r\n%%\r\nR=2; \r\nM=2;\r\nW=96;\r\nassert(tank(R,M)\u003eW)\r\n%%\r\nR=10; \r\nM=10;\r\nW=36;\r\nassert(tank(R,M)\u003eW)\r\n%%\r\nR=15; \r\nM=20;\r\nW=5;\r\nassert(tank(R,M)\u003cW)\r\n%%\r\nR=7; \r\nM=8;\r\nW=58;\r\nassert(tank(R,M)\u003cW)\r\n","published":true,"deleted":false,"likes_count":2,"comments_count":13,"created_by":166,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":285,"test_suite_updated_at":"2012-02-07T16:08:37.000Z","rescore_all_solutions":false,"group_id":35,"created_at":"2012-02-07T16:08:37.000Z","updated_at":"2026-05-24T23:19:20.000Z","published_at":"2017-10-16T01:50:58.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878;\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eAssume that there is a 100 liter tank.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eIt is initially filled with just distilled water.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eIt is continuously drained at R liters per minute.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eThis tank is always maintained full and homogeneous by continuously adding and stirring R liters per minute of an unknown acid (or some fancy oil if it helps you solving this problem).\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eHow many liters W of water will be in the tank after M minutes?\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eNeglect any expansion or contraction when the acid is mixed with water.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"problem_search":{"problems":[{"id":281,"title":"Acid and water","description":"\u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878;\r\n\r\nAssume that there is a 100 liter tank. \r\n\r\nIt is initially filled with just distilled water. \r\n\r\nIt is continuously drained at R liters per minute. \r\n\r\nThis tank is always maintained full and homogeneous by continuously adding and stirring R liters per minute of an unknown acid (or some fancy oil if it helps you solving this problem). \r\n\r\nHow many liters W of water will be in the tank after M minutes?\r\n\r\nNeglect any expansion or contraction when the acid is mixed with water. ","description_html":"\u003cp\u003e\u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878;\u003c/p\u003e\u003cp\u003eAssume that there is a 100 liter tank.\u003c/p\u003e\u003cp\u003eIt is initially filled with just distilled water.\u003c/p\u003e\u003cp\u003eIt is continuously drained at R liters per minute.\u003c/p\u003e\u003cp\u003eThis tank is always maintained full and homogeneous by continuously adding and stirring R liters per minute of an unknown acid (or some fancy oil if it helps you solving this problem).\u003c/p\u003e\u003cp\u003eHow many liters W of water will be in the tank after M minutes?\u003c/p\u003e\u003cp\u003eNeglect any expansion or contraction when the acid is mixed with water.\u003c/p\u003e","function_template":"function W = tank(R,M)\r\n  W = 100 * R * M;\r\nend","test_suite":"%%\r\nR=1; \r\nM=1;\r\nW=99;\r\nassert(tank(R,M)\u003eW)\r\n%%\r\nR=2; \r\nM=2;\r\nW=96;\r\nassert(tank(R,M)\u003eW)\r\n%%\r\nR=10; \r\nM=10;\r\nW=36;\r\nassert(tank(R,M)\u003eW)\r\n%%\r\nR=15; \r\nM=20;\r\nW=5;\r\nassert(tank(R,M)\u003cW)\r\n%%\r\nR=7; \r\nM=8;\r\nW=58;\r\nassert(tank(R,M)\u003cW)\r\n","published":true,"deleted":false,"likes_count":2,"comments_count":13,"created_by":166,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":285,"test_suite_updated_at":"2012-02-07T16:08:37.000Z","rescore_all_solutions":false,"group_id":35,"created_at":"2012-02-07T16:08:37.000Z","updated_at":"2026-05-24T23:19:20.000Z","published_at":"2017-10-16T01:50:58.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878; \u0026#9878;\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eAssume that there is a 100 liter tank.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eIt is initially filled with just distilled water.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eIt is continuously drained at R liters per minute.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eThis tank is always maintained full and homogeneous by continuously adding and stirring R liters per minute of an unknown acid (or some fancy oil if it helps you solving this problem).\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eHow many liters W of water will be in the tank after M minutes?\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eNeglect any expansion or contraction when the acid is mixed with water.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"errors":[],"facets":[[{"value":"Cody5:Hard","count":1,"selected":false}],[{"value":"medium","count":1,"selected":false}]],"term":"tag:\"fluid mixture\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}