The average marks obtained by a class of $60$ students is $05.$ The average marks of half of the students is found to be $85 .$ The average marks of the remaining students is

Of the three numbers, the average of the first and the second is greater than the average of the second and the third by $15 .$ What is the difference between the first and the third of the three numbers?

In an examination, out of $20$ students in a class, in Mathematics $2$ students scored $100$ marks $, 3$ students scored $0,$ and average marks for rest of the students was $40 .$ What is the average mark of the whole class ? (in $marks$)

The average contribution of $5$ men to a fund is $Rs.\,35.$ A sixth man joins and pays $Rs.\,35$ more than the resultant average of $6$ men. The total contribution of all the six men is (in $Rs.$)

The average of $11$ numbers is $10.9$ If the average of the first six is $10.5$ and the average of last six is $11.4,$ find the middle (sixth) number.

The average of $13$ results is $50 .$ If the average of first $7$ results is $52$ and that of last $7$ results is $49,$ find the $7^{th}$ result.