Video: Reading Data from Grouped Frequency Tables

Chris O’Reilly

The table shows the marks that a class of students received in a mathematics test. What percentage of the students scored at least 50 marks?

01:48

Video Transcript

The table shows the marks that a class of students received in a mathematics test. What percentage of the students scored at least 50 marks?

So when we’re looking to solve this problem, the key phrase is actually at least, because what we want is at least 50 marks. So therefore, this includes 50 marks. So therefore, it means that we’re actually interested in the last two groups, 50 to 54 marks and 55 marks plus. So therefore we can say that the number of students with at least 50 marks is going to be equal to six plus three, which is equal to nine.

Okay, so we’ve found the number of students that have at least 50 marks. However, the question wants us to find the percentage of students that scored at least 50 marks. So, great! We can use the answer from the first part, which is nine. And now let’s work out the percentage.

So therefore, we can say that the percentage of students is going to be equal to 9 over 41 multiplied by 100. And this nine is our numerator because that’s our subgroup, because that was the students with at least 50 marks, six plus three which gave us nine. And then 41 is our denominator because this is our total group. And if we look at the chart above, it tells us the total number of students was 41.

Okay, great! So now let’s calculate percentage. So this is gonna be equal to 900 over 41 percent, which if we convert into a mixed number is 21 and 39 over 41 percent. And we found that because 41 goes into 900 21 times with a remainder of 39. So therefore, we can say that the percentage of students who scored at least 50 marks is 21 and 39 over 41 percent.

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