Big Ideas Math: Modeling Real Life, Grade 7
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Exercise 3 Page 273

To write a percent as a decimal, move the decimal point two places to the left and remove the percent symbol. Use a 10 * 10 grid to represent this decimal.

Decimal: 2.21
Example Model Representation:

Practice makes perfect

Decimals and percents are ways to show parts of a whole.

Writing the Percent as a Decimal

To write a percent as a decimal, we ignore the percent symbol and move the decimal point two places to the left. Let's do it!

Percent to decimal
We found that 221 % expressed as a decimal is 2.21.

Representing the Decimal Using a Model

Now we want to represent 2.21 with a model. Begin by constructing a 10 * 10 grid — a total of 100 smaller squares. In this grid one square will correspond to 1 % or 0.01. Then the whole square represents 100 %.

Since 221 % is 221 parts out of 100 parts, we will color 221 small squares. <jsxgpre id="Solution_269081_3" alt="Model" static=0> var b = mlg.board([-2.5, 11.5, 38.5,-10], {desktopSize:'medium', style:'usa'}); var bb = b.board.getBoundingBox(); var buttons = []; var labs = ['Reset', 'Color the Squares'];

var n1 = b.node(0,0); var n2 = b.node(0,10); var n3 = b.node(10,10); var n4 = b.node(10,0);

var n5 = b.node(13,0); var n6 = b.node(13,10); var n7 = b.node(23,10); var n8 = b.node(23,0);

var n9 = b.node(13+13,0); var n10 = b.node(13+13,10); var n11 = b.node(23+13,10); var n12 = b.node(23+13,0);

var pol1 = b.polygon([n1,n2,n3,n4],{borders:{strokeColor:'darkviolet',opacity:0.3}}); var pol2 = b.polygon([n5,n6,n7,n8],{borders:{strokeColor:'darkviolet',opacity:0.3},color:'darkorange',opacity:0.5}); var pol3 = b.polygon([n9,n10,n11,n12],{borders:{strokeColor:'darkviolet',opacity:0.3},color:'darkorange',opacity:0.5});


var L = 11; /*Grid 1*/ var sp1 = b.segmentPoints(pol1.borders[0],L,{visible:false}); var sp2 = b.segmentPoints(pol1.borders[1],L,{visible:false}); var sp3 = b.segmentPoints(pol1.borders[2],L,{visible:false}); var sp4 = b.segmentPoints(pol1.borders[3],L,{visible:false}); for(var i=1;i<sp1.length-1;i++){ b.segment(sp1[i],sp3[L-1-i],{strokeWidth:1,strokeColor:'blue',opacity:0.3});

   b.segment(sp2[i],sp4[L-1-i],{strokeWidth:1,strokeColor:'blue',opacity:0.3});

}

/*Grid 2*/ var sp11 = b.segmentPoints(pol2.borders[0],L,{visible:false}); var sp21 = b.segmentPoints(pol2.borders[1],L,{visible:false}); var sp31 = b.segmentPoints(pol2.borders[2],L,{visible:false}); var sp41 = b.segmentPoints(pol2.borders[3],L,{visible:false}); for(var i=1;i<sp1.length-1;i++){ b.segment(sp11[i],sp31[L-1-i],{strokeWidth:1,strokeColor:'blue',opacity:0.3});

   b.segment(sp21[i],sp41[L-1-i],{strokeWidth:1,strokeColor:'blue',opacity:0.3});

}

/*Grid 3*/ var sp111 = b.segmentPoints(pol3.borders[0],L,{visible:false}); var sp211 = b.segmentPoints(pol3.borders[1],L,{visible:false}); var sp311 = b.segmentPoints(pol3.borders[2],L,{visible:false}); var sp411 = b.segmentPoints(pol3.borders[3],L,{visible:false}); for(var i=1;i<sp1.length-1;i++){ b.segment(sp111[i],sp311[L-1-i],{strokeWidth:1,strokeColor:'blue',opacity:0.3});

   b.segment(sp211[i],sp411[L-1-i],{strokeWidth:1,strokeColor:'blue',opacity:0.3});

}

var Rec = []; for(var j=1;j<3;j++){ for(var i=0;i<L-1;i++){ Rec.push(b.rectangle(b.node(sp2[j-1].X(),sp1[i].Y()),b.node(sp2[j].X(),sp1[i+1].Y()),{fillColor:"darkorange",fillOpacity:0.5,borders:{visible:false},visible:false})); }} Rec.push(b.rectangle(b.node(sp2[2].X(),sp1[0].Y()),b.node(sp2[3].X(),sp1[1].Y()),{fillColor:"darkorange",fillOpacity:0.5,borders:{visible:false},visible:false}));

/*animation*/ var per1 = b.segmentText(pol1.borders[3],{name:'0\\%',color:"darkorange",distance:1.5}); var per2 = b.segmentText(pol2.borders[3],{name:'100\\%',color:"darkorange",distance:1.5}); var per3 = b.segmentText(pol3.borders[3],{name:'100\\%',color:"darkorange",distance:1.5});

var f1 = b.polarnode(n1,-90,2); var f2 = b.polarnode(n12,-90,2); var Per = b.curlyBrace(f2,f1,{strokeWidth:1,label:{text:"200\\%\\text{ or } 2.00",distance:0,color:"darkorange"}});

var count=0; var F1 = function(){ var interval = setInterval(function(){ b.setAttribute(Rec[count],{visible:true,transitionDuration:250});

     	count++;
     	if(count > Rec.length){

clearInterval(interval);

           buttons[0].enable();
           buttons[0].setLabel(labs[0]);
           buttons[0].setDimension(60,30);

}else{

       	b.changeText(per1.text,count+"\\%");
       	b.changeText(Per.label,(200+count)+"\\% \\text{ or }"+b.round((200+count)/100,2));
       }

},250); };

var F2 = function(){ b.setAttribute(Rec,{visible:false});

   count=0;
   b.changeText(per1.text,count+"\\%");

b.changeText(Per.label,(200+count)+"\\% \\text{ or }"+b.round((200+count)/100,2));

   buttons[0].enable();

buttons[0].setLabel(labs[1]); buttons[0].setDimension(125,30); };

var kk = 0; var button = function(){ buttons[0].disable();

   if(kk%2==0){F1();}
   else{F2();}
   kk++;

};

buttons.push(b.button(0.5*(bb[0]+bb[2]),bb[3]+0.5, labs[1], button, {mathMode: false,width:125,anchor:"s"})); </jsxgpre>