Question

In a school, the ratio of boys to girls is 2:3. 20% of the boys are left handed 70% of the girls are right handed. What percentage of all the students are left handed?

Answer 1

Answer:

Step-by-step explanation:

Suppose we had a big animal sanctuary for cats and dogs.

We had say 30 cats and 50 dogs

So by proportion we have:  

Using format type 1

cats : dogs  

→

30

:

50

→

3

:

5

as ratio (proportions)

But for  

3

:

5

we have 3 parts in combination with 5 parts giving a proportion total of  

3

+

5

=

8

Converting this to fractions and hence percentage

Cats  

=

3

3

+

5

=

3

8

→

3

8

×

100

%

=

ddd

37.5

%

of the whole

Dogs  

=

5

3

+

5

=

5

8

→

5

8

×

100

%

=

ddd

62.5

%

of the whole

−−−−−−−−−−−−−−−−−−

ddddddddddddddddd

Added up  

→

100.0

%

all of the whole

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Using format type 2 - Fraction format

cats

dogs

→

30

50

→

3

5

←

This is NOT a fraction of the whole

Again we have  

cats

cats + dogs

→

3

3

+

5

×

100

%

=

37.5

%

of the whole

dogs

cats + dogs

→

5

3

+

5

×

100

%

=

62.5

%

of the whole

−−−−−−−−−−−−−−−−−−