Question 1143007
Since the interest rates differ by 4% and the interest amount of the higher rate is exactly double that of the lower, the first CD must pay 4% interest and the other CD must pay 8%.  <br>

---------------
<pre>
To see this algebraically: 

 P*r = 140           (1)
 P*(r+0.04) = 280    (2)

  P*r + 0.04P = 280
  140 + 0.04P = 280  <<< subs for P*r from (1)
        0.04P = 140
            P = 140/0.04 = 3500
 
    3500*(r+0.04) = 280
          r+0.04 = 280/3500 
          r+0.04 = 0.08  --->  r = 0.04 (= 4%)