The students in three classes are in the ratio 2 : 3 : 5. If 20 students are increased in each class. The ratio changes to 4 : 5 : 7. The total number of students before the increase were?

10
90
100
None of these

Correct Answer: 100

Explanation:

Let the number of students be 2x, 3x and 5x
∴ (2x + 20) : (3x + 20) : (5x + 20) = 4 : 5 : 7
⇒ (2x + 20)/4 = (3x + 20)/5 = (5x + 20)/7
⇒ 5(2x + 20) = 4(3x + 20)
∴ x = 10
Hence, total number of student before increase = 10x = 100.

← Previous Question Next Question→

More Questions from Ratio and Proportion

One year ago the ratio between Laxman's and Gopal's salary was 3 : 4. The ratio of their individual salaries between last year's and this year's salaries are 4 : 5 and 2 : 3 respectively. At present the total of their salary is Rs. 4,160. The salary of Laxman now is?
Three students A, B and C hired a computer for a month. A runs 27 floppy dics for 19 days, B runs 21 for 17 days and C runs 24 for 23 days. If at the end of the month, the rent amounts to ₹ 23700, how much amount outght to be paid by A?
The work done by (x + 2) men in (x - 3) days and work done by x men in (x - 2) days are equal. Find the value of x.?
1 yr ago, the ratio between mother and daughter age was 4 : 1. The ratio of their ages after 4 yr will be 3 : 1. Find the ratio of their ages 5 yr ago?
The ratio of expenditure and saving of a person is 26 : 3 . If his monthly income is ₹ 7250, then what is his monthly savings?
Three hikers A, B and C start on a trip with ₹ 50 each and agree to share the expenses equally. If at the end of the trip, A has ₹ 20 left with him, B ₹ 30 and ₹ 40, by how much amount must they settle their accounts?
₹ 1290 is divided between A, B and C, so that A's share is 1 1/ 2 times B's share and B's share is 1 3/ 4 C's share. What is C's share?
A started a business with a capital of ₹ 10000 and 4 months later , B joined him with a capital of ₹ 5000. What is the share of A in the total profit of ₹ 2000 at the end of the year?
On mixing two classes of students having average marks 25 and 40 respectively, the overall average obtained is 30 marks. Find the number of students in first class, if the second class has 30 students.?
In a mixture of 60 L, the ratio of milk and water is 2 : 1. If the ratio of milk and water is to be 1 : 2, then the amount of water to be further added must be?

Discussion & Comments

No comments yet. Be the first to comment!

Join Discussion