Question 1019207
The simple interest formula is I = Prt.

Now here, P = 3000, t = 4, and I = 960.  Substituting these values into the formula, we get 
960 = 3000*r*4
==> r = 2/25,or in percent, 8%.

Thus, the interest earned after 7 years would be 

I = 3000*0.08*7 = $1,680.