Can you help me understand this student's method for problem #3?

[halvizo1031]

can someone help me out on #3 please. I can't see the reasoning behind her work.

 

[Mentallic]

Her reasoning would make more sense if you jumped straight to answering b).

 

[halvizo1031]

I did look at b and her math is correct but it's the reasoning that I am not seeing. I would have just taken the original 4 scores, added the fifth score, and divided by 5.

 

[Mentallic]

Obviously both your method and hers are equivalent since they're both correct, but the process which is used is the only difference. It's somewhat similar to solving 5-2 by first starting with 5 and then taking away 2 as compared to solving -2+5 which is to first start with -2.

All I could do in explaining her reasoning would be to repeat exactly what the maths tells you.