Resolved: forcasting errors

Thank you for the question. Here is some additional information:

1.) MAPE:
MAPE = (1/n) * Σ(|Oi – Pi|/Oi * 100
where:
Pi is the predicted value for the ith observation
Oi is the observed value for the ith observation
n is the sample size

For calculation:
a) Online calculator: https://www.statology.org/mape-calculator/
b) With Excel: https://www.statology.org/mape-excel/
c) Python
https://scikit-learn.org/stable/modules/generated/sklearn.metrics.mean_absolute_percentage_error.html


2.) RMSE:
RMSE = sqrt [(Σ(Pi – Oi)²) / n]
Where:

Pi is the predicted value for the ith observation
Oi is the observed value for the ith observation
n is the sample size

For calculation:
a) Online calculator: https://www.statology.org/rmse-calculator/ 
b) With Excel: https://www.statology.org/root-mean-square-error-excel/
c) With Python: https://scikit-learn.org/stable/modules/generated/sklearn.metrics.root_mean_squared_error.html

I hope this helps.
Olivier