High School

We appreciate your visit to Class 10R sat a test The mean mark for the class was 70 There are 30 students in Class 10R 20 of whom are boys. This page offers clear insights and highlights the essential aspects of the topic. Our goal is to provide a helpful and engaging learning experience. Explore the content and find the answers you need!

Class 10R sat a test.

- The mean mark for the class was 70%.
- There are 30 students in Class 10R, 20 of whom are boys.
- The mean mark for the boys is 62%.

Work out the mean percentage mark for the girls.

Answer :

Answer:

86%

Step-by-step explanation:

You want the girls' average if the 20 boys in the 30-student class had an average of 62%, and the class average was 70%.

Weighted average

The class average is the weighted average of the boys' score and the girls' score. The weights are the fraction of students of each gender.

class average = (1/3)(girls' average) +(2/3)(boys' average)

Girls' average

Solving this equation for the girls' average, we get ...

(1/3)(girls' average) = (class average) -(2/3)(boys' average)

girls' average = 3(class average) -2(boys' average)

girls' average = 3(70%) -2(62%) = 210% -124%

girls' average = 86%

__

Alternate solution

The sum of differences from the class average must be zero. The boys' average is 8 points below the class average, and there are 2 times as many boys as girls. Thus, compared to the girls, the boys contribute a total of 2·8 = 16 points below the class average. The girls must counter by having an average 16 points above the class average: 70+16 = 86.

Thanks for taking the time to read Class 10R sat a test The mean mark for the class was 70 There are 30 students in Class 10R 20 of whom are boys. We hope the insights shared have been valuable and enhanced your understanding of the topic. Don�t hesitate to browse our website for more informative and engaging content!

Rewritten by : Barada