Question

if 75% of these students in a school are boys and the no.of girls is 420 , the no.of boys is​

Answer 1

Answer:

1260boys

Step-by-step explanation:

Let the number of students in the school be x.

As the number of girls is 420, number of boys = x-420.

So, according to the question,

75% of x = x - 420,

=> 75x/100 = x-420,

=> 3x/4 = x-420,

=> 3x = 4(x-420),

=> 3x = 4x-1680,

=> 4x-3x = 1680,

=> x = 1680.

Total number of students = x = 1680.

So, total number of boys =

75% of x,

=> 75x/100,

=> 75*1680/100,

=> 3*420,

=> 1260.

Hence, total number of boys = 1260

Answer 2

Answer:

1260

Step-by-step explanation:

No. of Girls - 420

Percentage of Girls - Total percentage - Percentage of boys

= 100 - 75

= 25%

25% = 420

1% = 420/25

1% = 16.8

No. of boys - 75*16.8

= 1260