If the average marks of three batches of $55, 60,$ and $45$ students are $50, 55,$ and $60$ respectively,then the average marks of all the students is:

The average age of $80$ boys in a class is $15.$ The average age of a group of $15$ boys in the class is $16$ and the average age of another $25$ boys in the class is $14.$ What is the average age of the remaining boys in the class?

The average of marks obtained by $120$ candidates was $35.$ If the average of marks of passed candidates was $39$ and that of failed candidates was $15,$ the number of candidates who passed the examination is

Of the three numbers, the second is twice the first and thrice the third. If the average of the three numbers is $44$, then the largest number is

The average of four consecutive odd numbers is $40$. What is the largest number?

$19$ persons went to a hotel for a combined dinner party. $13$ of them spent $Rs. 79$ each on their dinner and the rest spent $Rs. 4$ more than the average expenditure of all the $19$ persons. What was the total money spent by them?