An average mark is computed for 100 students in Business, an average is computed for 300 students in Arts, and an average is computed for 200 students in Science. The average of these three averages is 85%. However, the overall average for the 600 students is 86%. Also, the average for the 300 students in Business and Science is 4 marks higher than the average for the students in Arts. Determine the average for each group of students by solving a system of linear equations.

Kailyn Hamilton

Kailyn Hamilton

Answered question

2022-11-17

An average mark is computed for 100 students in Business, an average is computed for 300 students in Arts, and an average is computed for 200 students in Science. The average of these three averages is 85%. However, the overall average for the 600 students is 86%. Also, the average for the 300 students in Business and Science is 4 marks higher than the average for the students in Arts. Determine the average for each group of students by solving a system of linear equations.
Let x 1 , x 2 , x 3 represent the students in business, arts and science respectively.

100 x 1 + 300 x 2 + 200 x 3 = 86
100 x 1 + 200 x 3 + 4 = 300 x 2 Not sure as to how to create an equation for the first one.

Answer & Explanation

Gilbert Petty

Gilbert Petty

Beginner2022-11-18Added 23 answers


x = average business
y = average arts
z = average science
Just to say, the difference between the 85 and 86 equations is that the 85represents nonweighted averages, while the 86 is weighted.
Since you only want business to have 1 / 6 weight in the actual weighted average, you multiply it by 1 / 6. This is a slight problem with your first equation.
1 6 x + 3 6 y + 2 6 z = 0.86
(weighted average)
For the final equation, you can
For the average of averages, you just take the raw average
x + y + z 3 = 0.85
For the last one, we do another weighted average; however, this time, we are just weighting the business and science components. Because business makes up 100 of the 300 people in the field, we do 1 / 3, and for science, 2 / 3
1 3 x + 2 3 z 2 y = 0.04
To find the final answer, eliminate the z to get a two variable, two equation system of equations.

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