The average of 30 results is 20 and the average of other 20 results is 30 . what is the average of all the results?
Choose the correct option
A) 24
B) 25
C) 48
D) 50
E) none

Rationale: "answer sum of 50 result = sum of 30 result + sum of 20 result . = 30 x 20 + 20 x 30 = 1200 correct option : a"
Answer: A