The average marks of students in an examination was $65 .$ It was later found that the marks of one students had been wrongly entered as $83$ instead of $38.$ the correct average is ?

The average age of $8$ members of a group is $40 \,years.$ The age of $1$ member is $55\, years.$ After his retirement a new member comes in his place of age $39 .$ What is the effect of his retirement on the average age of group ?

The average of three numbers is $154 .$ The first number is twice the second and the second number is twice the third. The first number is

The average of five numbers is $6.9 .$ If one of the numbers is deleted, the average of the remaining numbers is $4.4 .$ What is the value of the number deleted?

The mean of $50$ observations was $36 .$ It was found later that an observation $48$ was wrongly taken as $23 .$ The corrected new mean is

$5$ members of a team are weighed consecutively and their average weight calculated after each member is weighed. If the average weight increases by one kg each time, how much heavier is the last player than the first one? (in $kg$)