The table shows the weights, approximated to the nearest kilogram, of 40 students. How many students weigh 45 kilograms or more?
So the key to answering this question is the fact that we’re looking for students that weigh 45 kilograms or more.
Now, if it just asked for the students who weighed 45 kilograms, then we wouldn’t be able to answer it. And the reason we wouldn’t be able to answer it is because this is a grouped frequency table.
And that means we don’t know the exact values of the students. So we know that there are seven between 45 and 49. But we don’t know what the individual weights of those seven students are.
So if we’re looking for 45 kilograms or more, then the only two columns that we’re interested in are the two that I’ve ticked. And that’s 45 to 49 and 50 to 54, because these are either 45 kilograms or more.
So therefore, to work out how many students weigh 45 kilograms or more, what we need to do is add seven and nine. We’re gonna add seven and nine because we’ve got seven students who weigh between 45 and 49 kilograms. And we have nine students who weigh between 50 and 54 kilograms.
So therefore, when we add these together, we get 16. So we can say that 16 students weigh 45 kilograms or more.