Question

The student of three classes are in the ratio 1:3:4 if 20 students of each class increased then the ratio become 5:7:8 Find the number of student first class before increased?​

Answer 1

Answer:

In the beginning, the three classes had 2x, 3x and 5x students where x is a constant of proportionality. 40 students were added in each section.

⇒ There are 2k+40,3k+40 and 5k+40 number of students in each section.

Given, 2k+40:3k+40:5k+40=4:5:7

⇒

3k+40

2k+40

=

5

4

⇒10k+200=12k+160⇒2k=40⇒k=20∴ Originally the total number of students was 2×20+3×20+5×20=200

Answer 2

Step-by-step explanation:

Let the number of students in the classes be 2x, 3x and 4x respectively;

Total students = 2x + 3x + 4x = 9x

Accordingtothequestion,

2x+12/3x+12=8/11

24x+96=22x+132

2x=132−96

x=36/2=18

Hence,9x=9×18=162