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.
Vasu said:
8 years ago
@Ramesh.
Your explanation is good and it is easy.
Your explanation is good and it is easy.
Praveen said:
8 years ago
Please slove.
40%of a number is more the 20% of 650 by 190 find the number with explanation.
40%of a number is more the 20% of 650 by 190 find the number with explanation.
Bisikesan behera said:
8 years ago
80%of x=48+2/3*48.
80/100=48+32,
4/5 x=80,
X=400/4=100.
80/100=48+32,
4/5 x=80,
X=400/4=100.
Kundan said:
8 years ago
Best explanation @Ramesh.
Agrim dev said:
8 years ago
Students who ages are 8 =48,
Students whose ages are above 8=2/3 of 48=32,
Students whose ages are below 8=20%=20(default as percentage is measured on 100)
Therefore total students=48+32+20=100.
Ans:100.
Students whose ages are above 8=2/3 of 48=32,
Students whose ages are below 8=20%=20(default as percentage is measured on 100)
Therefore total students=48+32+20=100.
Ans:100.
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.
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)
Renu said:
8 years ago
How to find 20%?
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.
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.
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