The youngest of 4 children has siblings who are 2, 7, and 11 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 25, what is the age of the youngest sibling?  Choose the most appropriate option:  A) 17  B) 18  C) 19  D) 20  E) 21
x + (x+2) + (x+7) + (x+11) = 100   4x + 20 = 100   4x = 80   x = 20   The answer is 20.
<result>D</result>
The youngest of 4 children has siblings who are 2, 7, and 11 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 25, what is the age of the youngest sibling?