In a Maths test the average score of the 10 girls in a class is 15 and the average score of the 15 boys is 10. The average score of the class in the test is
Answers
Given: 1. average score of 10 girls = 15 marks
2. average score of 15 boys= 10 marks
To find out : average score of the class
Solution :
1. for girls
Average =sum of observationsof girls/
total number of observations
15 = sum of observations of girls/
10
sum of observations of girls=15×10(transposing 10)
sum of observations of girls=150
2. for boys
average=sum of observations of boys/
total number of observations
10 = sum of observations of boys/
15
sum of observations of boys=10×15(transposing 15)
sum of observations of boys =150
3. for class
total number of observations (students)
=10 girls + 15 boys
=25 students
total sum of observations
= sum of observations of boys + sum of observations of girls
= 150 + 150
=300
average of class= total sum of observations/ total number of observations
=300
25
average of class=12 marks
Answer: the average marks of the class is 12marks.