In seven given numbers,the average of first four numbers is 4 and that of last four numbers is also 4. if the average of these seven numbers is 3, the fourth number is? Choose the correct answer:
A) 3 B) 4 C) 7 D) 11 E) 12
let 7 numbers are a,b,c,d,e,f,g.   given avg of first 4 nums are 4...i.e (a+b+c+d)/4=4   a+b+c+d=16   given avg of last 4 nums are also 4..i.e.(d+e+f+g)/4=4   d+e+f+g=16   e+f+g=16-d   given avg of 7 nums are 3....i.e (a+b+c+d+e+f+g)/7=3   a+b+c+d+e+f+g=21   16+16-d=21   d=32-21= 
<gadget id="calculator">32-21</gadget>
<output>11</output>
11   ANSWER:11
<result>D</result>
In seven given numbers,the average of first four numbers is 4 and that of last four numbers is also 4. if the average of these seven numbers is 3, the fourth number is?