# Khan/khan-exercises

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[i18n._("Gryffindor"), i18n._("Hufflepuff"), i18n._("Ravenclaw"), i18n._("Slytherin")] randRange( 0, HOUSES.length - 1 ) _.map(randRangeUnique(0, 9, HOUSES.length), function(n) { return n * 10; })

At Hogwarts, there are four houses: toSentence(HOUSES). The bar chart below shows the number of house points that each house received today.

How many house points did HOUSES[INDEX] receive?

init({ range: [[-2, 14], [-3, 11.5]], scale: [27, 30] }); _.times(10, function(y) { label([0, y], y * 10, "left", false); style({ stroke: "#000", strokeWidth: 1, opacity: 0.2 }, function() { line([0, y], [13, y]); }); }); _.each(VALUES, function(value, index) { style({ stroke: null, fill: "#9ab8ed", opacity: 1.0 }); path([[index * 3 + 1.5, 0], [index * 3 + 1.5, value / 10], [index * 3 + 2.5, value / 10], [index * 3 + 2.5, 0], true]); style({ opacity: 1.0 }); label([index * 3 + 2, 0], HOUSES[index], "below", false); }); style({ stroke: "#000", strokeWidth: 2, opacity: 1.0 }); line( [ 0, 0 ], [ 13, 0 ] ); line( [ 0, 0 ], [ 0, 10 ] ); label( [ 6.5, -0.8 ], i18n._("House"), "below", false ).css('font-weight', 'bold'); label( [ -1.5, 5 ], "House points", "center", false ).addClass( "rotate" ) .css('font-weight', 'bold'); label( [ 6.5, 10.5 ], "House points earned today", "above", false ).css('font-weight', 'bold');
VALUES[INDEX] house points

Find the bar for HOUSES[INDEX].

style({ stroke: PINK, fill: null, strokeWidth: 2 }); ellipse([INDEX * 3 + 2, -0.6], [1.5, 0.5]);

There is no bar for HOUSES[INDEX], which means HOUSES[INDEX] recieved 0 house points.

Compare the height of the bar for HOUSES[INDEX] to the scale on the left.

style({ stroke: PINK, strokeWidth: 2, arrows: "->", strokeDasharray: "-" }); line([INDEX * 3 + 1.5, VALUES[INDEX] / 10], [0, VALUES[INDEX] / 10]);