Question

A group of 100 students took a quiz. Their average score was 76 points. If the average score for the boys was 80 points and the average score for the girls was 70 points, how many girls participated in the quiz?

Answer 1

Answer:

The number of girls participated in quiz is 40 .

Step-by-step explanation:

Given as :

Total number of students took quiz = 100

Average score of 100 students = 76 points

The Average score of boys = 80 points

The Average score of girls = 70 points

Let The number of boys participated in quiz = b

Let The number of girls participate in quiz = g

Now, According to question'

Total number of students took quiz = number of boys participated in quiz + number of girls participated in quiz

Or, b + g = 100           ........A

Again

∵ Average score of 100 students = 76 points

∴ Total score of 100 students = 76 × 100 = 7600

So, Average score of boys × number of boys participated + Average score of girls × number of girls participated = Total score of 100 students

Or, b × 80 + g × 70 = 7600

Or, 80 b + 70 g = 7600             .........B

Now, Solving equation A and B

(80 b + 70 g ) - 70 ×( b + g ) = 7600 - 70 × 100

I.e (80 b - 70 b) + (70 g - 70 g) = 7600 - 7000

Or, 10 b + 0 = 600

∴  b = $\dfrac{600}{10}$

i.e b = 60

So, The number of boys participated in quiz = b = 60

Put the value of b into eq A

∵ b + g = 100

So, g = 100 - b

Or, g = 100 - 60

i.e g = 40

So, The number of girls participated in quiz = g = 40

Hence, The number of girls participated in quiz is 40 . Answer