EASY SUBTRACTING AND MULTIPLYING QUESTION
(not 128)

The answer is : x(n)=64

Option B 11 students is correct

Step-by-step explanation:

So your frequency table shows the different class intervals, which are ranges between the data that belong to specific classes. The frequency column shows how many observations fall into each class.

The problem states that we need to find those who received a score of 80 or better. So your range would be 80 and above.

Look at the classes that are within that range. The last two classes show the following intervals:

80 - 89

90 - 100

These are the classes where your intended group lie. So in the class 80-89 there are 7 students, and 90-100 there are 4. Just add them up to see how many received a score of 80 or better.

7 + 4 = 11 students.

This is what we call the cumulative frequency. These is the cumulative number of observations up to a certain class interval or range.

hope it will help :)