Question

In a group of students, 1/5 are under 8 years of age, out of the remaining 2/5 are over 8 years, how many parts of students are 8 years old​

Answer 1

Answer:

$\frac{2}{5}$

Step-by-step explanation:

Let the total numbers of student be 100.

Since, 1/5 are under 8 years of age.

∴ Total numbers of student under 8 years are $\frac{1}{5}  \times 100$ = 20

Since, 2/5  are over 8 years of age,

∴ Total numbers of student over 8 years are $\frac{2}{5}  \times 100$  = 40

∴ The remaining students are 8 years old exactly which is 40

∴ The fraction would be  40/100

parts of student who is 8 years old is 2/5

Answer 2

Given :

In a group of students, 1/5 are under 8 years of age, out of the remaining 2/5 are over 8 years,

To find :

how many parts of students are 8 years old​

Solution:

Part of students under 8 years =$\frac{1}{5}$

Remaining =$1-\frac{1}{5}=\frac{4}{5}$

out of the remaining 2/5 are over 8 years,

So, part of students over 8 years = $\frac{2}{5} \times \frac{4}{5}=\frac{8}{25}$

Let x be the parts of students are 8 years old​

So, $\frac{1}{5}+x+\frac{8}{25}=1\\\frac{5+25x+8}{25}=1\\13+25x=25\\25x=25-13\\25x=12\\x=\frac{12}{25}$

Hence 12/25  parts of students are 8 years old​