{"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":403,"title":"Einsteinium-253 decay","description":"Radioactive Einsteinium-253 has a half-life of 1,768,608 seconds.\r\nGiven 1000mg of Einsteinium-253 at t=0 days, how\r\nmuch is left after 50 days?\r\n\r\nEX: \u003e\u003e decay(50)\r\n\r\n184\r\n\r\nHINT: find k, then decay(50)\r\n\r\nUse: decay(t)=10^3*e^(k*t)\r\n\r\nNB: make sure you round your answer up to the next highest integer.","description_html":"\u003cp\u003eRadioactive Einsteinium-253 has a half-life of 1,768,608 seconds.\r\nGiven 1000mg of Einsteinium-253 at t=0 days, how\r\nmuch is left after 50 days?\u003c/p\u003e\u003cp\u003eEX: \u003e\u003e decay(50)\u003c/p\u003e\u003cp\u003e184\u003c/p\u003e\u003cp\u003eHINT: find k, then decay(50)\u003c/p\u003e\u003cp\u003eUse: decay(t)=10^3*e^(k*t)\u003c/p\u003e\u003cp\u003eNB: make sure you round your answer up to the next highest integer.\u003c/p\u003e","function_template":"function y = decay(x)\r\n  y = x;\r\nend","test_suite":"%%\r\nx = 50;\r\ny_correct = 184;\r\nassert(isequal(decay(x),y_correct))\r\n%%\r\nx = 60;\r\ny_correct = 132;\r\nassert(isequal(decay(x),y_correct))\r\n","published":true,"deleted":false,"likes_count":2,"comments_count":5,"created_by":1103,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":117,"test_suite_updated_at":"2012-02-25T06:40:53.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-25T06:00:27.000Z","updated_at":"2026-03-02T14:32:49.000Z","published_at":"2012-02-25T20:50:09.000Z","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\u003eRadioactive Einsteinium-253 has a half-life of 1,768,608 seconds. Given 1000mg of Einsteinium-253 at t=0 days, how much is left after 50 days?\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\u003eEX: \u003e\u003e decay(50)\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\u003e184\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\u003eHINT: find k, then decay(50)\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\u003eUse: decay(t)=10^3*e^(k*t)\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\u003eNB: make sure you round your answer up to the next highest integer.\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":403,"title":"Einsteinium-253 decay","description":"Radioactive Einsteinium-253 has a half-life of 1,768,608 seconds.\r\nGiven 1000mg of Einsteinium-253 at t=0 days, how\r\nmuch is left after 50 days?\r\n\r\nEX: \u003e\u003e decay(50)\r\n\r\n184\r\n\r\nHINT: find k, then decay(50)\r\n\r\nUse: decay(t)=10^3*e^(k*t)\r\n\r\nNB: make sure you round your answer up to the next highest integer.","description_html":"\u003cp\u003eRadioactive Einsteinium-253 has a half-life of 1,768,608 seconds.\r\nGiven 1000mg of Einsteinium-253 at t=0 days, how\r\nmuch is left after 50 days?\u003c/p\u003e\u003cp\u003eEX: \u003e\u003e decay(50)\u003c/p\u003e\u003cp\u003e184\u003c/p\u003e\u003cp\u003eHINT: find k, then decay(50)\u003c/p\u003e\u003cp\u003eUse: decay(t)=10^3*e^(k*t)\u003c/p\u003e\u003cp\u003eNB: make sure you round your answer up to the next highest integer.\u003c/p\u003e","function_template":"function y = decay(x)\r\n  y = x;\r\nend","test_suite":"%%\r\nx = 50;\r\ny_correct = 184;\r\nassert(isequal(decay(x),y_correct))\r\n%%\r\nx = 60;\r\ny_correct = 132;\r\nassert(isequal(decay(x),y_correct))\r\n","published":true,"deleted":false,"likes_count":2,"comments_count":5,"created_by":1103,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":117,"test_suite_updated_at":"2012-02-25T06:40:53.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-25T06:00:27.000Z","updated_at":"2026-03-02T14:32:49.000Z","published_at":"2012-02-25T20:50:09.000Z","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\u003eRadioactive Einsteinium-253 has a half-life of 1,768,608 seconds. Given 1000mg of Einsteinium-253 at t=0 days, how much is left after 50 days?\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\u003eEX: \u003e\u003e decay(50)\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\u003e184\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\u003eHINT: find k, then decay(50)\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\u003eUse: decay(t)=10^3*e^(k*t)\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\u003eNB: make sure you round your answer up to the next highest integer.\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":"easy","count":1,"selected":false}]],"term":"tag:\"isotope\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}