The equation for the area of a circle requires the radius, you put in the full diameter. Just divide 4.9 by 2, which gives you 2.45. 2.45 squared is equal to 6.0025 and then slap your pi on to the end of it.
So, we know the earned interest is 120, and we know the original deposited amount is 900 bucks, so, the accumulated amount will then be 900 + 120 or 1020 bucks.
