// Numbas version: exam_results_page_options
{"name": "Exponential population growth fully randomised", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Exponential population growth fully randomised", "tags": [], "metadata": {"description": "<p>Students are given an exponential equation and asked to evaluate it at two points.</p>\n<p>The constants in the exponential are randomised.</p>", "licence": "Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International"}, "statement": "<p>A population of bacteria has a population, $P$, that can be described by the function $P = \\var{k} \\times \\var{a}^t $, where $t$ is the time in {timeperiod}.</p>", "advice": "<p>a) When $t=0$,</p>\n<p>$&nbsp; P = \\var{k} \\times \\var{a}^t = \\var{k} \\times \\var{a}^0 = 1$</p>\n<p></p>\n<p>b) When $t = \\var{time}$,</p>\n<p>$P = \\var{k} \\times \\var{a}^\\var{time} = \\var{answer_raw}$</p>\n<p>When this is rounded to the nearest whole number, we get</p>\n<p>$P = \\var{answer}$</p>\n<p></p>\n<p>c) We need to take $t = -2$,</p>\n<p>$P = \\var{k} \\times \\var{a}^{-2} = \\var{ansc}$,</p>\n<p>When this is rounded to the nearest whole number, we get</p>\n<p>$P = \\var{ansc_r}$.</p>\n<p></p>\n<p>d) We need to solve the following equation:</p>\n<p>\\[\\var{l} = \\var{k} \\times \\var{a}^t\\]</p>\n<p>for $t$. Take the appropriate logarithm on both sides&nbsp;</p>\n<p>\\[log_{\\var{a}}(\\var{l}/\\var{k}) = \\var{ansd}\\]</p>", "rulesets": {}, "extensions": [], "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true}, "constants": [], "variables": {"objectchoice": {"name": "objectchoice", "group": "Ungrouped variables", "definition": "random(0..4)", "description": "", "templateType": "anything", "can_override": false}, "timeperiodlist": {"name": "timeperiodlist", "group": "Ungrouped variables", "definition": "['days','weeks','months','years']", "description": "", "templateType": "anything", "can_override": false}, "timeperiodchoice": {"name": "timeperiodchoice", "group": "Ungrouped variables", "definition": "random(0..3)", "description": "", "templateType": "anything", "can_override": false}, "timeperiod": {"name": "timeperiod", "group": "Ungrouped variables", "definition": "timeperiodlist[timeperiodchoice]", "description": "", "templateType": "anything", "can_override": false}, "k": 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"ansc", "group": "Ungrouped variables", "definition": "k*(a^(-2))", "description": "", "templateType": "anything", "can_override": false}, "ansc_r": {"name": "ansc_r", "group": "Ungrouped variables", "definition": "round(ansc)", "description": "", "templateType": "anything", "can_override": false}, "ansd": {"name": "ansd", "group": "Ungrouped variables", "definition": "log(l/k,a)", "description": "", "templateType": "anything", "can_override": false}, "time1": {"name": "time1", "group": "Ungrouped variables", "definition": "random(2..5)", "description": "", "templateType": "anything", "can_override": false}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": ["objectchoice", "timeperiodlist", "timeperiodchoice", "timeperiod", "k", "a", "time", "answer_raw", "answer", "l", "ansc", "ansc_r", "ansd", "time1"], "variable_groups": [], "functions": {}, "preamble": {"js": "", "css": ""}, "parts": [{"type": "numberentry", "useCustomName": false, "customName": "", "marks": "1", "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<p>What is the initial population, $P$, when $t$ = 0?</p>", "minValue": "{k}", "maxValue": "{k}", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "showFractionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"type": "numberentry", "useCustomName": false, "customName": "", "marks": "2", "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<p>What is the population, $P$, when $t = \\var{time}$ {timeperiod}</p>\n<p>Round your answer to the nearest whole number.</p>", "minValue": "round({k}*{a}^{time})", "maxValue": "round({k}*{a}^{time})", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "showFractionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"type": "gapfill", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<p>What was the population, $P$, {time1} {timeperiod} ago</p>\n<p>Round your answer to the nearest whole number.</p>\n<p>[[0]]</p>", "gaps": [{"type": "numberentry", "useCustomName": true, "customName": "gap 0", "marks": "2", "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minValue": "round({k}*{a}^{-time1})", "maxValue": "round({k}*{a}^{-time1})", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "showFractionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "sortAnswers": false}, {"type": "gapfill", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<p>When the population will reach $P=\\var{l}$. Give your answer accurate to 3 decimal places.&nbsp;</p>\n<p>$t =$[[0]] {timeperiod}</p>", "gaps": [{"type": "numberentry", "useCustomName": true, "customName": "gap 1", "marks": "2", "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minValue": "log({l}/{k}, a)", "maxValue": "log({l}/{k}, a)", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "precisionType": "dp", "precision": "3", "precisionPartialCredit": 0, "precisionMessage": "You have not given your answer to the correct precision.", "strictPrecision": false, "showPrecisionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "sortAnswers": false}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always", "contributors": [{"name": "Merryn Horrocks", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4052/"}, {"name": "Ugur Efem", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/14200/"}]}]}], "contributors": [{"name": "Merryn Horrocks", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4052/"}, {"name": "Ugur Efem", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/14200/"}]}