Making the world better, one answer at a time. a superbug is a micro-organism that is resistant to most anti-biotics. the superbugs in recent history are imune to all anti-biotics,except one.
Both electronic and paper versions of Series I savings bonds are purchased at face value and earn interest until they are redeemed or reach maturity. You must hold Series I bonds for at least 12 months before redeeming them. Series I savings bonds will continue to earn interest for up to 30 years. They will cease paying interest once they have matured.
Today (3/22/2012) the interest rate on the EE series savings bond is 0.6%. There was no way that an interest rate of 0.6% could lead to doubling of the value of a bond in 20 years. In fact, the value of the bond would increase less than 15% over the 20 years. The effective interest rate on EE Series savings bonds had to be a lot more than 0.60%. Using semi-annual compounding over 20 years, a $1000 bond will become $2001.60 (double in value) with an interest rate of of 3.5%.