The average quote for a 30-year fixed rate mortgage on Zillow’s mortgage marketplace last week was 4.14 percent. The average rate quoted for a 15-year loan was 3.6 percent.

And if you’re willing to take a flier on a 5/1 adjustable rate mortgage (ARM), the average quote was 2.96 percent.

Imagine getting a loan fixed for 5 years at under 3 percent. It’s hard to believe.

What’s even harder to believe is that the Federal Reserve Bank has decided to spend $600 billion buying bonds, a program known as “QE2,” short for the second round of quantitative easing.

The goal of the program is to lower long-term interest rates. The economic reasoning behind the purchases is that if long-term interest rates go down, economic activity will pick up, jobs will be created and the economic recovery will begin in earnest. And when that happens, those lower rates will spur the housing market to recover.

Will it work? It might, if everyone acts on those super-low interest rates. But will businesses hire more workers and make additional investments simply because the cost of borrowing drops another one-half of a percent? Is there a really big difference between borrowing money at 4 percent versus 3.5 percent? It seems unlikely that lowering interest rates would spur a business to act on landing a new client or an additional piece of business.

When it comes to mortgage refinancing the same principal applies. There is a finite number of homeowners who can refinance to take advantage of the super-low interest rates, either because they don’t have enough equity in their homes or because their credit score is shot or because they don’t have enough cash on hand to pay the closing costs or fees. Many of those who do have the cash, credit and equity necessary have already refinanced at record-low interest rates. Some have already refinanced a couple of times, as interest rates dropped.

Is it worthwhile to refinance again if you’ll only save $50 or $60 per month, but it will take 2 to 4 years to pay back the costs of the refinance with the savings the new lower rate will generate? And what about the costs you paid to refinance the last time?

At some point, the potential savings isn’t worth the effort.

There’s also some question about whether lower interest rates will spur home buyers to jump off the fence and make an offer.

Mortgage interest rates are nearly at 4 percent for a 30-year fixed-rate loan. But buying a home is a bigger decision than simply looking at how low interest rates are. You also have to have great credit and plenty of cash for closing costs and reserves. Many home buyers don’t have all those ducks in a row.

You also have to have a reason for moving: you desire a bigger house or a better school district; you want to take a new job; or, perhaps you’re ready to downsize and retire.

Will lowering interest rates overcome all of these other hurdles home buyers are facing? It’s tough to know.

One thing is for sure: Mortgage interest rates have never been this low. And if you do qualify to refinance and your current interest rate is over 5 percent on your 30-year or 15-year loan, you should run the numbers and figure out whether it makes sense for you financially to refinance your property.