Question

if class of 30 boys and 15 girls is given a test in maths .the average marks obtained by a boys 15 and girls 6. the average whole class is

Answer 1

Let the marks of boys be denoted by x₁, x₂, x₃....x₃₀

Let the marks of girls be denoted by y₁, y₂, y₃.... y₁₅

marks of boys:

(x₁+x₂+x₃....+x₃₀)/30 = 15

x₁+x₂+x₃...+x₃₀=450 →(1)

Average marks of girls:

(y₁+y₂+y₃....+y₁₅)/15=6

y₁+y₂+y₃....+y₁₅=90 → (2)

(1)+(2):

x₁+x₂+x₃...+x₃₀+y₁+y₂+y₃...+y₁₅=540

Total no of students=45

dividing both sides with 45:

(x₁+x₂+x₃...+x₃₀+y₁+y₂+y₃....+y₁₅)/45=12

Therefore the average marks of class is 12.

Answer 2

Answer:

21

Step-by-step explanation:

=Class has boys=30

=Class has girls=15

=average marks obtained by boys=15

=average marks obtained by girls=6

=15+6

=21