A student needed to find the arithmetic mean of the numbers 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x. He found the mean to be 12. What is the value of x?  Choose the correct choice from the following.
A) 12	B) 5	C) 7	D) 9	E) 10
Explanation:   3+11+7+9+15+13+8+19+17+21+14+x/12 =12   ⇒137+x12=12   ⇒137+x=144   ⇒x=144−137=7   Answer: Option 7
<result>C</result>
A student needed to find the arithmetic mean of the numbers 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x. He found the mean to be 12. What is the value of x?