Question

the table shows the number of students in each grade at prairie middle school. in the 8th grade, $\frac{4}{5}$ of students study chemistry. how many students in the 8th grade study chemistry? 100 students how many students are in the 8th grade? 100 students how do you find $\frac{4}{5}$ of a number? first, find $\frac{1}{5}$ of the number by dividing the number by? then multiply the result by?

Explanation:

Step1: Identify the total number of 8th - grade students

The table shows there are 100 students in 8th grade.

Step2: Determine the fraction of students studying chemistry

The fraction of 8th - grade students studying chemistry is $\frac{4}{5}$.

Step3: Calculate the number of 8th - grade students studying chemistry

To find $\frac{4}{5}$ of 100, first find $\frac{1}{5}$ of 100. Since $\frac{1}{5}$ of a number is found by dividing the number by 5, $100\div5 = 20$. Then, to find $\frac{4}{5}$ of the number, we multiply the result by 4. So $20\times4=80$. Also, we can directly calculate $\frac{4}{5}\times100=\frac{4\times100}{5}=80$.
To find $\frac{4}{5}$ of a number: First, find $\frac{1}{5}$ of the number by dividing the number by 5. Then multiply the result by 4.

Answer:

1. 80 students in the 8th grade study chemistry.
2. There are 100 students in the 8th grade.
3. First, find $\frac{1}{5}$ of the number by dividing the number by 5. Then multiply the result by 4.