Question

In a class of 30 plumbers, the average (arithmetic mean) score of the male plumbers on the final exam was 87. If the average score of 18 female plumbers in the class was 93, what was the average of the whole class?

Answer 1

What you have to do is add 87 and 93 then divide them by 2. 
(n+ n / p= a)
n= number
p= number of numbers add
a = average
The answer is 90. Hope this helps. Have a great day,