// Numbas version: finer_feedback_settings {"name": "Jo-Ann's copy of Division of fractions", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"advice": "
When faced with dividing fractions, it much easier to switch one of the fractions around and multiply them together instead of divide them.
\n\\[ \\left( \\frac{\\var{f_coprime}}{\\var{g_coprime}}\\div\\frac{\\var{h_coprime}}{\\var{j_coprime}} \\right) \\equiv \\left( \\frac{\\var{f_coprime}}{\\var{g_coprime}}\\times\\frac{\\var{j_coprime}}{\\var{h_coprime}} \\right) = \\frac{\\var{fj}}{\\var{gh}} \\]
\nThen, simplify by finding the highest common divisor in the numerator and denominator which in this case is $\\var{gcd1}$.
\nThis gives a final answer of $\\displaystyle\\simplify{{fj}/{gh}}$.
\n\n\\[ \\frac{\\var{f1_coprime}}{\\var{g1_coprime}}\\div\\frac{\\var{h1_coprime}}{\\var{j1_coprime}} \\equiv \\left( \\frac{\\var{f1_coprime}}{\\var{g1_coprime}}\\times\\frac{\\var{j1_coprime}}{\\var{h1_coprime}} \\right)=\\frac{\\var{f1j1}}{\\var{g1h1}} \\]
\nThen, simplify by finding the highest common divisor in the numerator and denominator which in this case is $\\var{gcd2}$.
\nThis gives a final answer of $\\displaystyle\\simplify{{f1j1}/{g1h1}}$.
\n\n\\[ {\\var{f3}\\frac{\\var{g3_coprime}}{\\var{h3_coprime}}}\\div{\\var{f4}\\frac{\\var{g4_coprime}}{\\var{h4_coprime}}} \\]
\nThe first thing to do is to change the mixed numbers into improper fractions.
\nAn improper fraction is a fraction where the numerator is greater than the denominator. To change a mixed fraction to an improper fraction, multiply the integer part of the mixed number by the denominator, and add it to the existing numerator to make the new numerator of the improper fraction. The denominator will stay the same.
\n\\[ {\\var{f3}\\frac{\\var{g3_coprime}}{\\var{h3_coprime}}}\\equiv\\frac{(\\var{f3}\\times\\var{h3_coprime})+\\var{g3_coprime}}{\\var{h3_coprime}}=\\frac{\\var{f3h3}+\\var{g3_coprime}}{\\var{h3_coprime}}=\\frac{\\var{f3h3+g3_coprime}}{\\var{h3_coprime}} \\]
\n\\[ {\\var{f4}\\frac{\\var{g4_coprime}}{\\var{h4_coprime}}}\\equiv\\frac{(\\var{f4}\\times\\var{h4_coprime})+\\var{g4_coprime}}{\\var{h4_coprime}}=\\frac{\\var{f4h4}+\\var{g4_coprime}}{\\var{h4_coprime}}=\\frac{\\var{f4h4+g4_coprime}}{\\var{h4_coprime}} \\]
\nWe now have our mixed numbers as improper fractions.
\n\\[ \\frac{\\var{f3h3+g3_coprime}}{\\var{h3_coprime}}\\div\\frac{\\var{f4h4+g4_coprime}}{\\var{h4_coprime}} \\]
\nNow, use the same method as in parts a) and b) to divide by switching around one fraction and changing the division symbol to multiplication.
\n\\[ \\frac{\\var{f3h3+g3_coprime}}{\\var{h3_coprime}}\\div\\frac{\\var{f4h4+g4_coprime}}{\\var{h4_coprime}}\\equiv\\frac{\\var{f3h3+g3_coprime}}{\\var{h3_coprime}}\\times\\frac{\\var{h4_coprime}}{\\var{f4h4+g4_coprime}}=\\frac{\\var{num}}{\\var{denom}} \\]
\nFinally, the last thing to do is to simplify your answer down by finding the highest common divisor in the numerator and denominator, which in this case is $\\var{gcd3}$.
\nBy doing this, you will get a final answer of
\n\\[ \\simplify{{num}/{denom}} \\]
\n\\[ \\frac{\\var{a}}{(\\simplify[all,!collectNumbers]{{b}-{c}/{d}})} \\]
\nConsider the denominator first, as following the rules of BODMAS, you should address brackets first.
\nYou need to get a common denominator for both terms on the denominator, like this:
\n\\[ \\var{b}\\times\\frac{\\var{d}}{\\var{d}} = \\frac{\\var{bd}}{\\var{d}} \\]
\nThis now allows you to complete the addition or subtraction as both terms have a common denominator.
\n\\[ {\\simplify[all,!collectNumbers]{{bd}/{d}-{c}/{d}}} = \\frac{\\var{bd_c}}{\\var{d}} \\]
\nThis means that the expression is now:
\n\\[ \\frac{\\var{a}}{\\frac{\\var{bd_c}}{\\var{d}}} \\]
\nDealing with this requires a bit of manipulation. You have to change the divisor of the denominator to be a mulitplier of the numerator. The denominator, ${\\var{bd_c}}$ was being divided by ${\\var{d}}$ but by flipping it around, the numerator, ${\\var{a}}$ will be mulitplied by ${\\var{d}}$. The value of the expression remains the same.
\n\\[ \\frac{\\var{a}}{\\frac{\\var{bd_c}}{\\var{d}}}\\equiv \\frac{(\\var{a})\\times(\\var{d})}{\\var{bd_c}}= \\frac{\\var{ad}}{\\var{bd_c}} \\]
\nFrom this, you can try to cancel the expression down by finding the highest common factor of the numerator and denominator, to give a final answer of
\n\\[ \\simplify{{ad}/{bd_c}} \\]
", "parts": [{"showFeedbackIcon": true, "variableReplacements": [], "marks": 0, "scripts": {}, "showCorrectAnswer": true, "variableReplacementStrategy": "originalfirst", "type": "gapfill", "prompt": "$\\displaystyle\\frac{\\var{f_coprime}}{\\var{g_coprime}}\\div\\frac{\\var{h_coprime}}{\\var{j_coprime}}=$
$\\displaystyle\\frac{\\var{f1_coprime}}{\\var{g1_coprime}}\\div\\frac{\\var{h1_coprime}}{\\var{j1_coprime}}=$
$\\displaystyle{\\var{f3}\\frac{\\var{g3_coprime}}{\\var{h3_coprime}}}\\div{\\var{f4}\\frac{\\var{g4_coprime}}{\\var{h4_coprime}}}=$
$\\displaystyle\\frac{\\var{a}}{(\\simplify[all,!collectNumbers]{{b}-{c}/{d}})} =$
Random number.
\nUsed in part c).
", "definition": "random(1..3)", "group": "part c", "name": "g3", "templateType": "anything"}, "f1j1": {"description": "variable f1 times j1.
\nUsed in part b).
", "definition": "f1_coprime*j1_coprime", "group": "part b", "name": "f1j1", "templateType": "anything"}, "h1": {"description": "Random number between 2 and 20.
\nUsed in part b).
", "definition": "random(2..10)", "group": "part b", "name": "h1", "templateType": "anything"}, "g1": {"description": "Random number between 2 and 30 and not the same value as variable f1.
\nUsed in part b).
", "definition": "random(f1..11 except f1) ", "group": "part b", "name": "g1", "templateType": "anything"}, "g4_coprime": {"description": "PART C
", "definition": "g4/gcd(g4,h4)", "group": "part c", "name": "g4_coprime", "templateType": "anything"}, "j1_coprime": {"description": "PART B
", "definition": "j1/gcd(h1,j1)", "group": "part b", "name": "j1_coprime", "templateType": "anything"}, "j": {"description": "Random number between 2 and 10 and not the same value as h.
\nUsed in part a).
", "definition": "random(h..12 except h)", "group": "part a", "name": "j", "templateType": "anything"}, "f3": {"description": "Random number between 2 and 6.
\nUsed in part c).
", "definition": "random(1..3#1)", "group": "part c", "name": "f3", "templateType": "randrange"}, "j1": {"description": "Random number between 2 and 20 and not the same value as variable h1.
\nUsed in part b).
", "definition": "random(h1..11 except h1)", "group": "part b", "name": "j1", "templateType": "anything"}, "g4": {"description": "Random number.
\nUsed in part c).
", "definition": "random(1..5)", "group": "part c", "name": "g4", "templateType": "anything"}, "fj": {"description": "variable f times variable j.
\nUsed in part a).
", "definition": "f_coprime*j_coprime", "group": "part a", "name": "fj", "templateType": "anything"}, "bd": {"description": "Variable b times variable d.
\nUsed in part d)
", "definition": "b*d", "group": "part d", "name": "bd", "templateType": "anything"}, "c": {"description": "Random prime number between -10 and 10.
\nUsed by part d).
", "definition": "random([-7,-5,-3,-2,-1,1,2,3,5,7] except d)", "group": "part d", "name": "c", "templateType": "anything"}, "num": {"description": "numerator of the improper fraction in part c. Unsimplified.
", "definition": "h4_coprime*(f3h3+g3_coprime)", "group": "part c", "name": "num", "templateType": "anything"}, "g3_coprime": {"description": "PART C
", "definition": "g3/gcd(g3,h3)", "group": "part c", "name": "g3_coprime", "templateType": "anything"}, "a": {"description": "Random number between 1 and 20
\nUsed by part d)
", "definition": "random(1..10#1)", "group": "part d", "name": "a", "templateType": "randrange"}, "f4": {"description": "Random number.
\nUsed in part c).
", "definition": "random(1..3)", "group": "part c", "name": "f4", "templateType": "anything"}, "bcd_gcd": {"description": "Correct answer for the denominator in part d).
", "definition": "{bd_c}/gcd", "group": "part d", "name": "bcd_gcd", "templateType": "anything"}, "gh": {"description": "variable g times variable h.
\nUsed in part a).
", "definition": "g_coprime*h_coprime", "group": "part a", "name": "gh", "templateType": "anything"}, "h4": {"description": "Random number but not the same number as variable g4.
\nUsed in part c.
", "definition": "random(5..8 except g4)", "group": "part c", "name": "h4", "templateType": "anything"}, "g1_coprime": {"description": "PART B
", "definition": "g1/gcd(f1,g1)", "group": "part b", "name": "g1_coprime", "templateType": "anything"}, "h3": {"description": "Random number and not the same value as variable g3.
\nUsed in part c).
", "definition": "random(5..8)", "group": "part c", "name": "h3", "templateType": "anything"}, "j_coprime": {"description": "PART A
", "definition": "j/gcd(h,j)", "group": "part a", "name": "j_coprime", "templateType": "anything"}, "h4_coprime": {"description": "PART C
", "definition": "h4/gcd(g4,h4)", "group": "part c", "name": "h4_coprime", "templateType": "anything"}, "h": {"description": "Random number from 2 to 10.
\nUsed in part a).
", "definition": "random(2..10)", "group": "part a", "name": "h", "templateType": "anything"}, "g": {"description": "Random number between 2 and 10 and not the same number as variable f.
\nUsed in part a).
", "definition": "random(f..12 except f) ", "group": "part a", "name": "g", "templateType": "anything"}, "h_coprime": {"description": "PART A
", "definition": "h/gcd(h,j)", "group": "part a", "name": "h_coprime", "templateType": "anything"}, "h1_coprime": {"description": "PART B
", "definition": "h1/gcd(h1,j1)", "group": "part b", "name": "h1_coprime", "templateType": "anything"}, "f4h4": {"description": "variable f4 times h4.
\nUsed in part c)
", "definition": "f4*h4_coprime", "group": "part c", "name": "f4h4", "templateType": "anything"}, "g1h1": {"description": "variable g1 times h1.
\nUsed in part b).
", "definition": "g1_coprime*h1_coprime", "group": "part b", "name": "g1h1", "templateType": "anything"}, "d": {"description": "Random prime number between 10 and 20.
\nUsed in part d).
", "definition": "random(7,11,13,17)", "group": "part d", "name": "d", "templateType": "anything"}, "b": {"description": "Random number between 1 and 10.
\nUsed by part d)
", "definition": "random(1..10#1)", "group": "part d", "name": "b", "templateType": "randrange"}, "gcd3": {"description": "greatest common denominator for part c.
", "definition": "gcd(num,denom)", "group": "part c", "name": "gcd3", "templateType": "anything"}, "f_coprime": {"description": "PART A
", "definition": "f/gcd(f,g)", "group": "part a", "name": "f_coprime", "templateType": "anything"}, "h3_coprime": {"description": "PART C
", "definition": "h3/gcd(g3,h3)", "group": "part c", "name": "h3_coprime", "templateType": "anything"}, "ad_gcd": {"description": "Correct answer for the numerator in part d)
", "definition": "ad/gcd", "group": "part d", "name": "ad_gcd", "templateType": "anything"}, "gcd1": {"description": "greatest common divisor of variable fj and gh.
\nUsed in part a).
", "definition": "gcd(fj,gh)", "group": "part a", "name": "gcd1", "templateType": "anything"}, "bd_c": {"description": "Unsimplified denominator for part d).
", "definition": "(bd-c)", "group": "part d", "name": "bd_c", "templateType": "anything"}, "gcd2": {"description": "greatest common divisor of variables f1j1 and g1h1.
\nUsed in part b).
", "definition": "gcd(f1j1,g1h1)", "group": "part b", "name": "gcd2", "templateType": "anything"}, "g_coprime": {"description": "PART A
", "definition": "g/gcd(f,g)", "group": "part a", "name": "g_coprime", "templateType": "anything"}, "f1": {"description": "Random number between 2 and 20.
\nUsed in part b)
", "definition": "random(2..10)", "group": "part b", "name": "f1", "templateType": "anything"}, "f": {"description": "Random number between 2 and 10.
\nUsed in part a).
", "definition": "random(2..10)", "group": "part a", "name": "f", "templateType": "anything"}, "f1_coprime": {"description": "PART B
", "definition": "f1/gcd(f1,g1)", "group": "part b", "name": "f1_coprime", "templateType": "anything"}, "ad": {"description": "Variable a times variable d.
\nUsed in part d).
", "definition": "a*d", "group": "part d", "name": "ad", "templateType": "anything"}, "denom": {"description": "Unsimplified denominator of part c.
", "definition": "h3_coprime*(f4h4+g4_coprime)", "group": "part c", "name": "denom", "templateType": "anything"}, "f3h3": {"description": "variable f3 times h3.
", "definition": "f3*h3_coprime", "group": "part c", "name": "f3h3", "templateType": "anything"}, "gcd": {"description": "Greatest common divisor of ad and bd_c.
\nUsed in part d).
", "definition": "gcd(ad,bd_c)", "group": "part d", "name": "gcd", "templateType": "anything"}}, "preamble": {"js": "", "css": "fraction {\n display: inline-block;\n vertical-align: middle;\n}\nfraction > numerator, fraction > denominator {\n float: left;\n width: 100%;\n text-align: center;\n line-height: 2.5em;\n}\nfraction > numerator {\n border-bottom: 1px solid;\n padding-bottom: 5px;\n}\nfraction > denominator {\n padding-top: 5px;\n}\nfraction input {\n line-height: 1em;\n}\n\nfraction .part {\n margin: 0;\n}\n\n.table-responsive, .fractiontable {\n display:inline-block;\n}\n.fractiontable {\n padding: 0; \n border: 0;\n}\n\n.fractiontable .tddenom \n{\n text-align: center;\n}\n\n.fractiontable .tdnum \n{\n border-bottom: 1px solid black; \n text-align: center;\n}\n\n\n.fractiontable tr {\n height: 3em;\n}\n"}, "ungrouped_variables": [], "variable_groups": [{"variables": ["a", "b", "c", "d", "bd", "ad", "gcd", "ad_gcd", "bcd_gcd", "bd_c"], "name": "part d"}, {"variables": ["f", "g", "f_coprime", "g_coprime", "h", "j", "h_coprime", "j_coprime", "fj", "gh", "gcd1"], "name": "part a"}, {"variables": ["f1", "g1", "f1_coprime", "g1_coprime", "h1", "j1", "h1_coprime", "j1_coprime", "f1j1", "g1h1", "gcd2"], "name": "part b"}, {"variables": ["f3", "g3", "h3", "g3_coprime", "h3_coprime", "f4", "g4", "h4", "g4_coprime", "h4_coprime", "f3h3", "f4h4", "num", "denom", "gcd3"], "name": "part c"}], "metadata": {"description": "Several problems involving dividing fractions, with increasingly difficult examples, including mixed numbers and complex fractions.
", "licence": "Creative Commons Attribution 4.0 International"}, "variablesTest": {"maxRuns": 100, "condition": ""}, "statement": "Evaluate the following sums involving division of fractions. Simplify your answers where possible.
", "name": "Jo-Ann's copy of Division of fractions", "functions": {}, "tags": ["dividing fractions", "division of fractions", "fractions", "Fractions", "mixed numbers", "taxonomy"], "type": "question", "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}, {"name": "Lauren Richards", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/1589/"}, {"name": "Jo-Ann Lyons", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/2630/"}]}]}], "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}, {"name": "Lauren Richards", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/1589/"}, {"name": "Jo-Ann Lyons", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/2630/"}]}