Complete the frequency table which shows the marks a group of students received in a test.
The table tells us that there were a total of 50 students. We also know the number of students who received each group of marks with the exception of 45 to 49 marks. Our first step is to add the frequencies of those students who received between 20 and 24, 25 and 29, 30 and 34, 35 and 39, 40 and 44, and more than 50 marks.
We need to add four, five, 15, nine, 10, and four. Adding these six numbers gives us a total of 47 students.
As 47 students are represented in these six groups, the remainder of students must have received between 45 and 49 marks in the test. We need to subtract 47 from 50, the total number of students. 50 minus 47 is equal to three. This means that three students received between 45 and 49 marks.
So the missing number in the frequency table is three. We could check this by once again adding all of the frequencies. And our total would be 50.