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?
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:
135 comments Page 7 of 14.
Ramasubramanian said:
8 years ago
Very good explanation @Ramesh.
Md jakir hossain said:
8 years ago
Thanks for the given explanation.
Lavanya said:
8 years ago
@Ramesh.
They mentioned 20%.
Is that right to mention it as simply 20?
They mentioned 20%.
Is that right to mention it as simply 20?
Santosh shah said:
8 years ago
Below 8 year= 20,
Exact 8 year= 48,
Above 8 year = 2/3 * 48 = 32.
So, total students=100.
Exact 8 year= 48,
Above 8 year = 2/3 * 48 = 32.
So, total students=100.
Deepan said:
8 years ago
Hi, According to me,
We are calculating upto 80% and what about remaining 20%?
So, [80%+20%]=[100+25],
No.of students = 125.
We are calculating upto 80% and what about remaining 20%?
So, [80%+20%]=[100+25],
No.of students = 125.
Abhishek said:
8 years ago
Let the total no of students be =x.
Then 20% of student are below 8 years, means x *20/100 =x/5 --------> eqn 1
Now 48 student are 8 years old --------> eqn2.
And no of the student which is above 8 years is 2/3 of 48 ie 32 --------> eqn3.
So by eqn 2 and 3 by addition 48+32=80.
So we add 20 more to make it 100 so answer is 100.
Then 20% of student are below 8 years, means x *20/100 =x/5 --------> eqn 1
Now 48 student are 8 years old --------> eqn2.
And no of the student which is above 8 years is 2/3 of 48 ie 32 --------> eqn3.
So by eqn 2 and 3 by addition 48+32=80.
So we add 20 more to make it 100 so answer is 100.
Aarthy said:
8 years ago
As specified by the question, we can rewrite it as x= 20/100*x+48+2/3 (48). Where x be the total number of students in the school and by solving the above expression, we get the answer as 100.
That's all. Simple.
That's all. Simple.
Renu said:
8 years ago
How to find 20%?
Ashoka said:
8 years ago
2/3(students of 8 years age) = 48.
So number of age of 8 years students is 48*3/2 = 72.
And number of students above 8 years age is 48.
So we can conclude 80% of students of class is 72+48 = 120.
Therefor 100% of students number become 120*100/80 = 150.
So students of below 8 years age is 30.
So number of age of 8 years students is 48*3/2 = 72.
And number of students above 8 years age is 48.
So we can conclude 80% of students of class is 72+48 = 120.
Therefor 100% of students number become 120*100/80 = 150.
So students of below 8 years age is 30.
(1)
Ashish Kumar Biswas said:
8 years ago
Let,
Total number of student = x.
Given as,
8 years age = 48
8 years above age = 48 *(2/3)
= 32.
Below 8 years age = x*20%
By condition,
X*20%+32+48 = x
Or, x*(20÷100) +80 = x
Or, x - x/5 =80
Or, (5x-x)/5 = 80
Or,4x/5 = 80
Or, x = (80*5)/4
Or, x = 100
So, total number of student = 100.
Ans: 100.
Total number of student = x.
Given as,
8 years age = 48
8 years above age = 48 *(2/3)
= 32.
Below 8 years age = x*20%
By condition,
X*20%+32+48 = x
Or, x*(20÷100) +80 = x
Or, x - x/5 =80
Or, (5x-x)/5 = 80
Or,4x/5 = 80
Or, x = (80*5)/4
Or, x = 100
So, total number of student = 100.
Ans: 100.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers