The number of students in 3 classes are in the ratio 4:5:6. If 15 stud...
Solution:
Let the number of students in the three classes be 4x, 5x, and 6x.
After increasing 15 students in each class, the number of students becomes 4x + 15, 5x + 15, and 6x + 15.
According to the question,
(4x + 15) : (5x + 15) : (6x + 15) = 11 : 13 : 15
Multiplying both sides by 3, we get
(4x + 15) * 3 : (5x + 15) * 3 : (6x + 15) * 3 = 33 : 39 : 45
Simplifying, we get
4x + 45 : 5x + 45 : 6x + 45 = 33 : 39 : 45
Multiplying both sides by 5, we get
20x + 225 : 25x + 225 : 30x + 225 = 165 : 195 : 225
Dividing both sides by 5, we get
4x + 45 : 5x + 45 : 6x + 45 = 33 : 39 : 45
Subtracting 30 from each term, we get
4x + 15 : 5x + 15 : 6x + 15 = 3 : 4 : 5
Now, we can write
4x + 15 = 3y
5x + 15 = 4y
6x + 15 = 5y
Solving these equations, we get
x = 15
Therefore, the number of students in the three classes in the beginning was
4x + 5x + 6x = 15(4+5+6) = 15(15) = 225
Hence, the correct answer is option (B) 150.
The number of students in 3 classes are in the ratio 4:5:6. If 15 stud...
Let the number of students in the classes be 4x, 5x and 6x respectively;
Total students = 4x + 5x + 6x = 15x.
Given, (4x+15)/(5x+15) = 11/13
3x=30==>x=10.
Then Total no of students is 15x=15*10=150.