// Numbas version: exam_results_page_options {"name": "James's copy of Numerical Reasoning - percentage enlargement", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "James's copy of Numerical Reasoning - percentage enlargement", "parts": [{"variableReplacementStrategy": "originalfirst", "prompt": "

What percentage of the size of the original picture was the final copy?

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[[0]] %

", "type": "gapfill", "marks": 0, "variableReplacements": [], "gaps": [{"marks": 1, "minValue": "final", "variableReplacementStrategy": "originalfirst", "type": "numberentry", "maxValue": "final", "allowFractions": false, "variableReplacements": [], "showPrecisionHint": false, "correctAnswerFraction": false, "scripts": {}, "showCorrectAnswer": true}], "scripts": {}, "showCorrectAnswer": true}], "ungrouped_variables": ["dir1", "dir2", "final", "prop1", "prop2", "prop2rel", "verbed1", "verbed2"], "advice": "

The picture has been {verbed1} to {prop1}% or $\\simplify{{prop1}/100} \\left(=\\frac{\\var{prop1}}{100}\\right)$ of its original size.

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So to find the size of the first copy we multiply the original size by $\\simplify{{prop1}/100}$.

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If we then {verbed2} the new size by {prop2}%, the final copy would be {prop2rel}% of the size of the first copy, i.e. $\\simplify{{prop2rel}/100}$ of the size of the first copy.

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To get the size of the final copy as a proportion of the size of the original copy, we multiply $\\simplify{{prop1}/100}$ by $\\simplify{{prop2rel}/100}$ to get

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\\[\\simplify{{prop1}/100} \\times \\simplify{{prop2rel}/100} = \\simplify{{prop1*prop2rel}/10000}\\]

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Now to express this as a percentage we multiply by 100 and we obtain:

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\\[\\simplify{{prop1*prop2rel}/10000} \\times 100 = \\var{final}\\%.\\]

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So the final copy is {final}% of the size of the original picture.

", "variablesTest": {"condition": "", "maxRuns": 100}, "variable_groups": [], "statement": "

A picture on a page was {verbed1} on a copier to {prop1}% of its original size, and this copy was then {verbed2} by {prop2}%.

", "preamble": {"css": "", "js": ""}, "functions": {}, "type": "question", "metadata": {"notes": "", "licence": "Creative Commons Attribution 4.0 International", "description": "

Scale a page to some percentage of its original size, then increase/decrease by another percentage. Find the size of the final copy as a percentage of the original.

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Based on question 2 from section 3 of the Maths-Aid workbook on numerical reasoning.

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