Cumulative grade not match with Percent Equivalent in Excel computation

Good Day every-one and to the Admin.

I made an input with Markbook.
Weightings are set accordingly:
– Performance = 50% of the Grade
– Written = 30% of the Grade
– Assessment = 20% of the Grade
But when I compared it to excel computations, the result do not match.

Is there any step I missed?

Thank you in advance.

@ross please could you look into this one for Rady? Thanks!

Dear Admin, @ross :

As a follow-up, I wish the decimal value of the “Cumulative” will remain with decimal when exported to excel.
Again, thank you in advance for this request.