In the US, there are a number of variations for CPR, depending on the responder and patient and possibly the number of responders.
If the responder is a "professional" responder, someone trained in Healthcare Provider-level CPR (BLS or ALS) then single-responder CPR is a ratio of 30:2 compressions to breaths, assuming proper kit is available, this applies to infants, children and adults. If there are two responders, then the ratio for infants and children changes to 15:2, again assuming the proper kit is available.
For responders trained to a lower level, without kit, then hands-only CPR is recommended. In US emergency response systems (E911 areas) with Emergency Medical Dispatchers, the dispatcher is trained to walk completely untrained responders through the steps to provide hands-only CPR when appropriate.
Incidentally, there are a couple of Youtube clips that actors/celebrities have done as PSA's for hands-only CPR. One was a
Staying Alive clip done for the American Heart Association by Ken Jeong from the 2009 movie The Hangover. What makes this interesting is that in addition to the actor being a comedian, he is also a licensed MD.
My personal favourite though, is this
PSA clip Vinnie Jones did for the British Red Cross. The
mini-Vinnie CPR clip is pretty good too.