Aptitude - Percentage - Discussion

Discussion Forum : Percentage - General Questions (Q.No. 7)
7.

In a certain school, 20% of students are below 8 years of age. The number of students above 8 years of age is of the number of students of 8 years of age which is 48. What is the total number of students in the school?

72
80
120
150
100
Answer: Option
Explanation:

Let the number of students be x. Then,

Number of students above 8 years of age = (100 - 20)% of x = 80% of x.

80% of x = 48 + 2 of 48
3

80 x = 80
100

x = 100.

Video Explanation: https://youtu.be/yPfocU6DA2M

Discussion:
140 comments Page 2 of 14.

JPE said:   2 years ago
No.of students of 8 yrs - 48.
No.of students of above 8 yrs - 2/3 of 8 yrs old stud.
So, 2/3*48 = 32.
Total students of 8 yrs and above 8 yrs = 48 + 32 = 80 students.

Now, out of the total students, only 20% of them are below 8 years old. We don't know how many are total students yet. So let's assume the total students as X.
Students below 8 years old -X*20/100(20% is written as 20/100).
= 20x/100.

Total students in school,
80(8yr & above 8 yr total) + 20x/100(below 8yrs total) = x(total students in school that we assumed as x).
80 + 20x/100 = x.
//Take LCM for 80+20x/100.
(8000+20x)/100 = x.
//Bring the denominator 100 to the right side to multiply with x.
8000 + 20x = 100x.
8000 = 80x.
x = 100.
(17)

Hemant Asthana said:   4 years ago
x is a total number of students. Then According to the question,
x = 48 + 2/3*48 + 20% of x,
x = 48 + 32 + x/5,
4x/5 = 80,
x = 100 (total number of students).
(16)

Sathwika Chirra said:   4 months ago
Given 20%(x) = below 8 years.
above 8 years = 2/3(8 years),
= 2/3(48),
= 32.
Now 48 + 32 + 20%(x) = x
80 + 20/100(x) = x.
4x = 400.
x = 100.
(16)

Vaibhav kumar singh said:   4 years ago
If 20 % = above 8 years so , 80 % = below 8 years + exact 8 years.
therefore 80 % ----> 2/3 of 48=32 (below 8 years) + 48(exact).
80% ---------> 80.
100% ---------> 100.
So, ans = 100.
(14)

Gokulavasan said:   3 years ago
Below 8 years is 20%.
Above 8 and equal to 8 years is 80%.

The number of students above 8 years of age is 2/3 of the number of students of 8 years of age which is 48.

1/3 of 48 students is 16.
2/3 of the students are 32.
1/3+2/3 = 48 (8 years).
16 students (above 8 years),
48 + 32 = 80 equal and above 8 years,
80% = 80 then,
20% = 20.
Total 100 students.
(13)

Prasanth Shanmugam said:   3 years ago
@All.
Here is my solution.

Total Number of Students = X.
Less than 8 Years age Students = 20 % of X = (20/100) * X.
8 Years Age Students = 48,
c = (2/3) * 48 = 32.

Total Number of Students = X = Less than 8 Years age Students + 8 Years Age Students + 8 Years Age Students
X = (20/100) * X + 48+32.
X = (20/100) * X + 80.
X = (20X+8000)/100.
100X = 20X+8000.
80X = 8000.
X = 8000/80.
Total Number of Students = X= 100.
(12)

Aryan Shrivastava said:   2 months ago
Students of exact 8 years old = 48,
Student who is 8+ = 2/3(48) = 24.

This all makes 80% of students, which is 48 + 24 = 72.
It means if 80% = 72.
20% = 18
(80 + 20)%= 72 + 18.
100% = 100.
(12)

Abel lula shonk said:   3 years ago
Thank you everyone.
(9)

Ishika said:   7 months ago
Thank you all for explaining it.
(7)

RAMESH said:   2 decades ago
Below 8 years = 20
Exact 8 years = 48
Above 8 years = 2/3*48 = 32
TOTAL OF THE ABOVE =100
(6)


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