Task: Question Answering
Input (English): Problem: a school has 4 section of chemistry in class x having 50 , 35 , 45 and 42 students . the mean marks obtained in chemistry test are 50 , 60 , 55 and 45 respectively for the 4 sections . determine the overall average of marks per student . 
Options: a ) 50.12 , b ) 52.12 , c ) 51.12 , d ) 53.12 , e ) none of the above
Output (English): b