Question

The students in three classes are in the ratio 2 : 3 : 5 If 40 students are increased in each class the ratio changes to 4 : 5 : 7 Originally the total number of students was

• A. 100
• B. 180
• C. 200
• D. 400

Answer 1

Answer: (C)

200

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.
$\Rightarrow$ 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
$\Rightarrow \frac{2k+40}{3k+40}=\frac{4}{5}\Rightarrow 10k+200=12k+160\Rightarrow 2k=40\Rightarrow k=20\therefore$ Originally the total number of students was $2\times 20+3\times 20+5\times 20=200$