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 4 of 14.
Robin Loomba said:
1 decade ago
Total number of students = x.
According to the condition:
20% of student below 8 years + 48 (8 years student) + (2/3)*48 above 8 years = x (total number of students).
20% of x + 48 + 32 = x.
(20/100)*x + 80 = x.
80 = x-x/5.
80 = 4x/5.
x = 100.
According to the condition:
20% of student below 8 years + 48 (8 years student) + (2/3)*48 above 8 years = x (total number of students).
20% of x + 48 + 32 = x.
(20/100)*x + 80 = x.
80 = x-x/5.
80 = 4x/5.
x = 100.
Ashish jain said:
1 decade ago
Why 48 is added?
Sankarshan said:
1 decade ago
What ever may be the % of students below 8 years,
Let x be the no of students below 8 years.
So ,
(2/3)x = 48;
x = (48*3)/2;
x = 72;
So total no of students = 72+48 = 120.
Why this answer is wrong?
Let x be the no of students below 8 years.
So ,
(2/3)x = 48;
x = (48*3)/2;
x = 72;
So total no of students = 72+48 = 120.
Why this answer is wrong?
Pinal patel said:
1 decade ago
Why 48+2/3 of 48?
Rumman said:
1 decade ago
LET TOTAL STUDENT BE X.
THEN STUDENT BELOW AGE 8=20% OF X=20/100 OF X.
STUDENT EXACTLY AT 8 = 48.
STUDENT ABOVE 8 = 2/3 OF 48 = 32.
20X/100+48+32 = X;
20X+4800+3200 = 100X;
80X = 8000;
X = 100;
SIMPLE.
THEN STUDENT BELOW AGE 8=20% OF X=20/100 OF X.
STUDENT EXACTLY AT 8 = 48.
STUDENT ABOVE 8 = 2/3 OF 48 = 32.
20X/100+48+32 = X;
20X+4800+3200 = 100X;
80X = 8000;
X = 100;
SIMPLE.
Naresh said:
1 decade ago
Can you explain me when should we take 100-20 in the above given problem and then whats the need to consider it for 100%?
Saif Alam said:
1 decade ago
Let total student = x.
Below 8 year = 20% of x i.e x/5.
Exact 8 year = 48.
Above 8 year = 2/3*48=32.
So,
Total student = x/5 + 48 + 32.
x = x/5 + 80.
x-x/5 = 80.
4x = 400.
x = 100.
Below 8 year = 20% of x i.e x/5.
Exact 8 year = 48.
Above 8 year = 2/3*48=32.
So,
Total student = x/5 + 48 + 32.
x = x/5 + 80.
x-x/5 = 80.
4x = 400.
x = 100.
Debasmita said:
1 decade ago
Answer should be 150.
Explanation:
Let, x = no. of student at 8 years old.
Above 8 years old = 2/3 of x.
=> x = 48*(3/2) = 72.
Students above 8 years and 8 years old = 72+48 = 120.
If (100-20)% = 80% equals 120 students.
1% equals 120/80.
100% equals (120/80)*100 = 150.
Explanation:
Let, x = no. of student at 8 years old.
Above 8 years old = 2/3 of x.
=> x = 48*(3/2) = 72.
Students above 8 years and 8 years old = 72+48 = 120.
If (100-20)% = 80% equals 120 students.
1% equals 120/80.
100% equals (120/80)*100 = 150.
Mahi said:
1 decade ago
How came 2/3?
Shrihari said:
1 decade ago
Hi answer is 100.
Here they mentioned above 8 year old students are 2/3 of 48 of age 8.
So 2/3 of 48 = 32.
So 32+48 = 80.
Now we left with 20% of students which are below 8.
There will be maximum 100% so they asking 20%.
We already found 80% of the students strength i.e. 80.
So 20% of 100 is 20. So 80(8 year+above 8 year) + 20(less than 8) = 100.
Hope you guys got it.
Here they mentioned above 8 year old students are 2/3 of 48 of age 8.
So 2/3 of 48 = 32.
So 32+48 = 80.
Now we left with 20% of students which are below 8.
There will be maximum 100% so they asking 20%.
We already found 80% of the students strength i.e. 80.
So 20% of 100 is 20. So 80(8 year+above 8 year) + 20(less than 8) = 100.
Hope you guys got it.
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