// Numbas version: finer_feedback_settings
{"name": "Percentages: decrease - evaporation", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Percentages: decrease - evaporation", "tags": [], "metadata": {"description": "<p>Given x and y, calculate (x-y) as a percentage of y.&nbsp; Chemistry context.</p>", "licence": "None specified"}, "statement": "", "advice": "<p><strong>METHOD 1:</strong></p>\n<p>When calculating a percentage decrease we need to know:</p>\n<p>- the original amount ({og}g)<br/>- the actual decrease ({og} - {new} = {og-new}g)</p>\n<p>Now find the decrease as a percentage of the original, using the formula</p>\n<p>\\[ \\text{Percentage in decimal form} = \\frac{\\text{Decrease}}{\\text{Original volume}} \\]</p>\n<p>So, to work out $\\var{og-new}$ as a percentage of $\\var{og}$,</p>\n<p>\\[ \\begin{split} \\text{Percentage in decimal form} &amp;\\,= \\frac{\\var{og-new}}{\\var{og}} \\\\ &amp;\\,= \\var{(100-p)/100} \\end{split} \\]</p>\n<p>To express our in answer as a percentage rather than in decimal form, we need to multiply this answer by $100$.</p>\n<p>Therefore the percentage loss is $\\var{(100-p)} \\% $</p>\n<p></p>\n<p><strong>METHOD 2:</strong></p>\n<p>We could calculate the percentage remaining, and then subtract this from 100%</p>\n<p>i.e.&nbsp;</p>\n<p>\\[ \\text{Percentage in decimal form} = \\frac{\\text{New volume}}{\\text{Original volume}} \\]</p>\n<p>\\[ \\begin{split} \\text{Percentage in decimal form} &amp;\\,= \\frac{\\var{new}}{\\var{og}} \\\\ &amp;\\,= \\var{(p)/100} \\end{split} \\]</p>\n<p>the remaining percentage is $\\var{(p)} \\% $, meaning the decrease (or loss) is $100 - \\var{p} =&nbsp;\\var{(100-p)} \\% $</p>\n<p></p>", "rulesets": {}, "extensions": [], "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true}, "constants": [], "variables": {"p": {"name": "p", "group": "Ungrouped variables", "definition": "random(60..99)", "description": "", "templateType": "anything", "can_override": false}, "og": {"name": "og", "group": "Ungrouped variables", "definition": "random(101..999)", "description": "", "templateType": "anything", "can_override": false}, "new": {"name": "new", "group": "Ungrouped variables", "definition": "og*p*0.01", "description": "", "templateType": "anything", "can_override": false}}, "variablesTest": {"condition": "new<og", "maxRuns": "15"}, "ungrouped_variables": ["p", "og", "new"], "variable_groups": [], "functions": {}, "preamble": {"js": "", "css": ""}, "parts": [{"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>{og}ml of liquid is measured in a beaker.</p>\n<p>After 12 hours, {new}ml is measured.</p>\n<p>What is the percentage decrease in the liquid due to evaporation?</p>\n<p>[[0]]%</p>", "gaps": [{"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, "minValue": "100-p", "maxValue": "100-p", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "showFractionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "sortAnswers": false}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always", "type": "question", "contributors": [{"name": "Ruth Hand", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/3228/"}, {"name": "Ben McGovern", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4872/"}]}]}], "contributors": [{"name": "Ruth Hand", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/3228/"}, {"name": "Ben McGovern", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4872/"}]}