semester average

[AIMEE]

my exhusband and I are in battle. My daughter, age 13 has a semester report card and we need help in calculating her average semester grade for each class.
For example: (For each class)
1st six week grade 86
2nd 84
3rd 82
semester exam 78
I said to:
add 82+78=160 div. by 2=80+84+86=250 div. by 3=83.3
he claims I am wrong, even though I came up with the exact totals that her report card had.
How do I prove or disprove my formula?
Please help this mom on a mission. We both have a problem with being wrong and the kids enjoy the show! ha, ha..

 

[stapel]

How do I prove or disprove my formula?

The only way to be certain of the grading algorithm is to consult with the instructor and/or the course syllabus. :idea:

Eliz.

 

[AIMEE]

Thank you. I have a call into the school.
Aimee

 

[tkhunny]

Note: The school may not be interested in your arithmetic. They may have their grades done by very sophiticated programs coded by very bright programmers. Wheteher they are wrong or right, it will be a very hard fight to get them to see that you have a point of view. I once demonstrated irrefutably that a local school district's grading program weighted partial year courses too heavily. This meant that sports-capable students were given unfairly high grades, and that kids with asthma were given unfairly low grades. In any case, they weren't interested. It persists to this day now eight or so years later. Good luck though. If nothing else, your daughter may learn that her parents are willing to fight for her. This certainly can be a valuable lesson.

 

[Loren]

In my opinion it depends on how the scores are weighted. If they are all weighted the same, then your husband is correct.
(86+84+82+78)÷4 = 82.5
However, suppose they want the semester exam to be worth twice as much as the six week's grades. Then we would have (86+84+82+2x78)÷5 = 81.6

Or, maybe they averaged the semester exam with the average of the six week's grades. Then it would be ((86+84+82)÷3) + 78)÷2=81.

Or, they have some other formula such as the one you came up with. Yours treats the average of the 3rd six weeks and the semester exam as having the same weight as the 1st and 2nd week's grades. If your daughter is on a trimester plan I can see the reasoning, somewhat. If she is on a quarter plan, then I don't see the rational for your method.

Your formula has the 1st six weeks score and the second 6 week's score being weighted twice as much as each of the last two scores. This gives you (2x86 + 2x84 + 82 + 78)÷6 = 83.3.