Video Transcript
Descending cumulative frequency
diagrams have been drawn to represent the grades achieved in a test by students
in two classes, class A and class B. Determine which class has more
students achieving a grade of 40 or higher.
The descending cumulative
frequency of a value 𝑥 gives us the frequency, or number of values, that are
equal to or greater than 𝑥. Given the descending cumulative
frequency graphs for classes A and B, we can use these to determine the number
of students in each class who achieved a grade of 40 or more. We draw a vertical line on each
graph from 40 on the 𝑥-axis until it meets the curve and then a horizontal line
from this point to the 𝑦-axis.
We observe that in the graph
for class A, the line meets the 𝑦-axis at 17. In the graph for class B, the
line meets the 𝑦-axis at 13. This means that class A has 17
students achieving a grade of 40 or more and that class B has 13 students
achieving 40 or more. As 17 is greater than 13, we
can give the answer that class A has more students achieving a grade of 40 or
higher.
