Data weight averaging say I have 2 datasets and need to get an average but with a weight based on the number of students.

school 1  = 98.1 . (50 students)
School 2 = 95.4 .   (169 students)

How would i get the average of both with a weighted average reflected the average of the student totals i think it would be around   = 96.ish

thanks for any insight!
There are 50 + 169 = 219 students in total. 
The weights are 50/119 = 0.23 and 169/219 = 0.77 respectively. 

Hence, 0.23*98.1 + 0.77*95.4 = 96.021