Find the average of the following set of scores $253,124,255,534,836,375,101,443,760$

A batch of $60$ students made an average score of $50$ marks and another batch of $40$ students made it only $45 .$ What is the overall average score ?

The average weight of $8$ sailors in a boat is increased by $1\, kg$ if one of them weighting $56\,kg$ is replaced by a new sailor. The weight of the new sailor is (in $kg$)

The average age of board of directors of a company, having $10$ directors was $48$ years. Coincidentally when a director aged $53$ resigned from the board of directors, another director died on the same day. So a new director joined the board of directors aged $34.$ Next year in the same month the average age of all the $9$ directors was found to be $46 \,years.$ The age of the late (i.e., dead) director at the time of his death was (in $years$)

The average weight of $6$ persons is increased by $5\, kg$ when one of them who weighs $40\, kg$ is replaced by a new man. The weight of new man is (in $kg$)

The average of six numbers is $20 .$ If one number is removed, the average becomes $15 .$ What is the number removed ?