Question

2/5 of the number of students of a class are girls.

i) Find the percentage of girls.

ii) Find the percentage of boys.​

Answer 1

Answer:

i) 2/5 × 100 = 40%

ii) 100% - 40% = 60%

Answer 2

Step-by-step explanation:

Given :-

2/5 of the number of students of a class are girls.

To find:-

i) Find the percentage of girls.

ii) Find the percentage of boys.

Solution:-

Let the number of students in a class be X

Number of girls in the class = 2/5th of the students

=> (2/5)×X

=> 2X/5

Percentage of girls = (Number of girls/Total number of students) × 100

=>[ (2X/5)/(X) ]×100

=> (2X/5X) ×100

=> (2×100)/5

=> 200/5

=> 40%

Number of boys in the class =

=> X-(2X/5)

=> (5X-2X)/5

=> 3X/5

Percentage of boys = (Number of boys/Total number of students) × 100

=>[ (3X/5)/(X)]×100

=> (3X/5X)×100

=> (3×100)/5

=> 3×20

=> 60%

Short cut:-

Girls = 2/5

Boys = 1-(2/5) = (5-2)/5 = 3/5

Total = (2/5)+(3/5)=5/5=1

Girls% = (2/5)×100=40%

Boys %= (3/5)×100 = 60% or

100%-40%=60%

Answer:-

1) The percentage of girls = 40%

2) The percentage of boys = 60%