When deciding how much of their income to save for retirement should workers consider the real or the nominal interest rate that their savings will earn Explain?

In this case the Real Rate of Return (RRR) should be used. A worker saving for his retirement, will be concerned with how much goods his money will be able to buy after finishing work. That is why the inflation should be taken into acount. If using nominal rates you would see how much stuff would you be able to buy TODAY with the amount you will have when retired.