the average marks of a class of 30 students is 40 and that of another class of 50 students is 60 . find the average marks of all the students ?
"sum of the marks for the class of 30 students = 30 * 40 = 1200 sum of the marks for the class of 50 students = 50 * 60 = 3000 sum of the marks for the class of 80 students = 1200 + 3000 = 4200 average marks of all the students = 4200 / 80 = 52.5 answer : d"
divide(add(multiply(30, 40), multiply(50, 60)), add(30, 50))