Interpreting bar graphs (colors) | Math | 3rd grade | Khan Academy

Chelsey asks 600 people at her school their favorite color and graphs the results. Some colors are not on Chelsea's graph. How many people chose colors other than those on Chelsea's graph?

So, here's Chelsea's graph: she made a bar graph and she listed some favorite colors: blue, green, red, yellow, pink, and graphed people who had those favorite colors. But some of these 600 people, like me, had a different favorite color. My favorite color, orange, isn't on the graph, so we're asked how many people like me were not graphed.

How many people picked a color besides blue, green, red, yellow, and pink? So, the way we can figure this out is if we look at the graph and figure out how many of the 600 people are on the graph. Then we can take that away from the total 600 people to find out how many are not on the graph.

So, we'll start by looking at the graph. First one: blue. This bar lines up to 90. So, 90 people picked blue. Plus next one: green. It lines up to 135. One hundred and thirty-five people picked green. Moving over to red, this bar lines up to seventy-five. Seventy-five more picked red. Yellow and pink: the bars are the same heights, which means the same amount of people picked yellow and red, and we can move over and see that that was one hundred and twenty. So, one hundred and twenty picked yellow and another one hundred and twenty picked red.

If we combine all of these numbers, combined all the people that are on the graph, that will help us to figure out how many are not on the graph. So, let's start. Let's start with the ones: zero ones plus five ones is five ones. Plus five more ones is ten. Well, zero is still ten. Plus zero is still ten. So, we have ten ones.

Plus let's look at our tens: nine tens plus three tens is twelve tens. Twelve tens plus seven tens is nineteen tens. Nineteen tens plus two is twenty-one tens. Two more tens: twenty-one tens plus two more tens is twenty-three tens. So, we have twenty-three tens, or 230. That's zero because we're talking about tens.

Plus we can now do our hundreds. Only a few of these had hundreds: we had one hundred plus another hundred is two hundreds, plus another hundred is three hundreds. So, three hundreds. We have two zeros. Now we're talking about hundreds: three hundreds. If we add all these together, ten plus 230, 230 is 240, and 240 plus 300, well let's see, that will still be 40, but 200 plus another 300 is 500. So, 540 people are on the graph.

But we're asked how many are not on the graph. So, up here we see there are 600 total people who were asked. 600 total people and we want to take away the 540 who were on the graph. That will tell us how many were not on the graph.

If we take these people away, everybody who's left is like me, whose favorite color is not on the graph. So, let's do that. If we started with 600 and we're subtracting 540, let's first subtract the 500. 600 minus 500 is 100. But we still need to subtract the 40. 100 is like ten tens minus 40, which is 4 tens. Ten tens minus 4 tens is 6 tens, or 60.

So, there were 60 people who chose colors other than those on Chelsea's graph.