Question

In a maths test (out of 20 marks maximum) the 13 boys in the class scored a
mean of 12 marks. The 12 girls' mean was 15 marks. What was the mean for
the whole class? (1 d.p.)​

Answer 1

Step-by-step explanation:

Let their salaries be 9x and 7x.

Let their expenditure be 4y and 3y.

According to the question,

9x−4y=2000           —(1)

7x−3y=2000            —(2)

From (1)

x=92000+4y              —(3)

On putting x in (2), we get

7×9(2000+4y)−3y=2000

9(14000+28y)−3y=2000

914000+28y−27y=2000

14000+y=18000

y=4000

Now, put y in (3)

x=92000+4×4000

x=92000+16000

x=918000=2000

So,

Salary of first person =9×2000=Rs. 18000

Salary of second person =7×2000=Rs. 14000

Hence, this is the answer.