Question

In a college of 405 students the ratio between the number of boys and girls is 7:2. if the number of boys and girls is raised by 50 and the ratio of boys and girls comes to be 3:1, then find the increase in the number of boys.​

Answer 1

Answer:

Answer is 105

Step-by-step explanation:

Total students = 405

Boys : Girls = 7:2

= 7x + 2x = 9x

ATQ

9x = 405

x = 405/9 = 45

So boys = 45×7 = 315

girls = 45×2 = 90

The number of girls is raised by 50

So :- 90 + 50 = 140

New ratio is :- 3:1

315 + x / 140 = 3 / 1

315 + x = 420

x = 420 - 315

= 105 answer

Answer 2

The increase in number of boys is 27.

Given - Original number of students, ratio of boys and girls, increased students

Find - Increased number of boys

Solution - Let the original number of boys and girls he 7x and 2x.

So, 7x + 2x = 405

9x = 405

x = 405/9

x = 45

Original number of boys = 7x

Original number of boys = 7*45

Original number of boys = 315

Increased total number of students = 405 + 50

Increased total number of students = 455

Let the new number of boys and girls be 3x and 1x.

So, 3x + 1x = 455

4x = 455

x = 455/4

x = 113.75

Since number of boys and girls can't be in decimal, hence, taking the value as 114.

New number of boys = 3x

New number of boys = 3*114

New number of boys = 342

Increased number of boys = 342 - 315

Increased number of boys = 27

Hence, the increased number of boys is 27.

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