// Numbas version: exam_results_page_options
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It is known that $X$ follows a Normal distribution with a mean of {chosen_m}{chosen_units} and a standard deviation of {chosen_s}{chosen_units}.</p>\n<p>&nbsp;</p>", "advice": "<p></p>\n<p>If&nbsp;{percentage}% of {chosen_item}s contain less than {x}&nbsp;{chosen_units} then we can&nbsp;write&nbsp;$P(X &lt; x ) = \\var{prob}$</p>\n<p>Using the Standard Normal tables we can write $P(Z &lt; \\var{z1}) = \\var{prob}$</p>\n<p>Now $x = \\mu + z \\times \\sigma$</p>\n<p>so that $x = \\var{chosen_m}&nbsp;+ (\\var{z1}\\times \\var{chosen_s})= \\var{x1}$</p>\n<p>&nbsp;</p>", "rulesets": {}, "extensions": ["stats"], "variables": {"prob1": {"name": "prob1", "group": "Ungrouped variables", "definition": "precround(1-p,2)", "description": "", "templateType": "anything"}, "Index": {"name": "Index", "group": "Ungrouped variables", "definition": "random(0,1)", "description": "", "templateType": "anything"}, "prob3": {"name": "prob3", "group": "Ungrouped variables", "definition": "precround(p1-p2,2)", 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"Ungrouped variables", "definition": "1-p", "description": "", "templateType": "anything"}, "prob2": {"name": "prob2", "group": "Ungrouped variables", "definition": "precround(1-p1,2)", "description": "", "templateType": "anything"}, "chosen_amount": {"name": "chosen_amount", "group": "Ungrouped variables", "definition": "amount[Index]", "description": "", "templateType": "anything"}, "zupper": {"name": "zupper", "group": "Ungrouped variables", "definition": "precround((upper-chosen_m)/chosen_s,2)", "description": "", "templateType": "anything"}, "stuff": {"name": "stuff", "group": "Ungrouped variables", "definition": "[\"flour in a packet\", \"soft drink in a bottle\"]", "description": "", "templateType": "anything"}, "amount": {"name": "amount", "group": "Ungrouped variables", "definition": "[\"number of grams\", \"volume (in ml)\"]", "description": "", "templateType": "anything"}, "chosen_s": {"name": "chosen_s", "group": "Ungrouped variables", "definition": "s[Index]", "description": "", "templateType": "anything"}, "chosen_stuff": {"name": "chosen_stuff", "group": "Ungrouped variables", "definition": "stuff[index]", "description": "", "templateType": "anything"}, "units1": {"name": "units1", "group": "Ungrouped variables", "definition": "[\"g\", \"ml\"]", "description": "", "templateType": "anything"}, "zlower": {"name": "zlower", "group": "Ungrouped variables", "definition": "precround((chosen_m-lower)/chosen_s,2)", "description": "", "templateType": "anything"}, "chosen_item": {"name": "chosen_item", "group": "Ungrouped variables", "definition": "item[Index]", "description": "", "templateType": "anything"}, "prob": {"name": "prob", "group": "Ungrouped variables", "definition": "percentage/100", "description": "", "templateType": "anything"}, "p": {"name": "p", "group": "Ungrouped variables", "definition": "precround(normalcdf(zlower,0,1),4)", "description": "", "templateType": "anything"}, "tol": {"name": "tol", "group": "Ungrouped variables", 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