Among 7 Numbers the Average of first four numbers is 13 and the average of last four numbers is 15. The sum of last three numbers is 55. The square of the fourth Number is equal to the last number then what is the last number? Pick
A) 60  B) 52  C) 5  D) 25  E) 125
let the numbers be a,b,c,d,e,f,g   d+e+f+g = 15 * 4= 
<gadget id="calculator">15 * 4</gadget>
<output>60</output>
60   e+f+g= 55, 60 - 55 = 5   so the fourth number is 5. The square is 25.   the answer is Option 25.
<result>D</result>
Among 7 Numbers the Average of first four numbers is 13 and the average of last four numbers is 15. The sum of last three numbers is 55. The square of the fourth Number is equal to the last number then what is the last number?