<prompt> Normal QRS duration at 1 year of age is0.03-0.07 seconds0.04-0.08 seconds0.04-0.09 seconds0.06-0.09 seconds  <response>: Normal QRS duration at various age groups Age group QRS duration in seconds 0-6 months 0.03-0.07 0.05 1-5 yr 0.04-0.08 0.06 10-15 yr 0.04-0.09 0.07 15 yr 0.06-0.09 0.08 Reference: Essential Paediatrics; O.P. Ghai; Page no: 459 