3girls and 2 boys took part in a quiz. the girls scored a total of 21 marks and the boys scored a total of 19 marks what was the average score

3 girls and 2 boys took part in a quiz
total all students took the quiz = 3 + 2 = 5 students

the girls scored a total of 21 marks and the boys scored a total of 19
total score of all students = 21 + 19 = 40

Average = 40/5 = 8

Answer
Average score = 8

it is C 10

Step-by-step explanation:

 If the positions are distinct, as in executive offices, then P(9, 5). 

P(9, 5) = 9!/(9 - 5)! = 15120 

If the positions are equivalent, such as seats in a legislative body, then C(9, 5). 

C(9, 5) = 9!/[(9 - 5)!(5!)] = 126

Assuming the five positions are unique in their duties and responsibilities (i.e. order matters): position 1 has 9 candidates to choose from, position 2 has 8, position 3 has 7, and so on. Otherwise, if you're talking about 5 distinct but duplicate positions - meaning their responsibilities are the same but 5 people are required to carry them out - you need to divide the previous total number of possibilities by the number of ways those possibilities could have been reordered.