Some data points count more than others. Multiply each by its weight, sum, then divide by total weight.
Weighted mean
(Σwᵢxᵢ) / (Σwᵢ)
Try it
Test 1 (50 marks, 20% weight), Test 2 (80, 80%)
(0.2·50 + 0.8·80)/(0.2 + 0.8) = (10 + 64)/1 = 74.
Some data points count more than others. Multiply each by its weight, sum, then divide by total weight.
Test 1 (50 marks, 20% weight), Test 2 (80, 80%)
(0.2·50 + 0.8·80)/(0.2 + 0.8) = (10 + 64)/1 = 74.