9) In a football team there are 11 players. The average age is 22 years. During a match, a player is sent off; the average age of the remaining players then becomes 21 years. How old is the player who was sent off?
(A) 22 years
(B) 23 years
(C) 28 years
(D) 32 years
(E) 33 years.
9) The answer is (D). The sum of the ages of all the players is $22 \times 11=242$ years. When the player who was sent off leaves, the sum of the ages becomes $21 \times 10=210$ years. Therefore, the player who got injured is $242-210=32$ years old.