Question

In a class there are 70 students. Ratio of boys
and girls is 4: 3. If average marks of whole
class are 80% and average marks of all the
boys are 86%. Then what is the average marks
of all the girls?

Answer 1

Answer:

72

40 boys got 240 marks extra

these 240 marks cut by 30 girls

8 percent less

so it is 72

Answer 2

In a class there are 70 students.                                      ( given)

Ratio of boys and girls is 4: 3.                                           ( given)

Number of boys in the class = 70 × $\frac{4}{7}$= 40.

∴ number of girls = (70 - 40 )= 30

Average marks obtained by whole class = 80%              ( given)

Total marks obtain by whole class = 70 ×80= 5600

Average marks obtained by 40 boys = 86%                     ( given)

Now we will find out total marks obtain by 40 boys = 40 ×86= 3340

Hence total marks obtained by 30 girls = ( 5600 -3440)=2160

The average marks of all the girls= $\frac{2160}{30}$ = 72

∴The average marks of all the girls will be 72%.

Ans :- The average marks of all the girls will be 72%.

#SPJ3