Final answer:
Earth is approximately 4.5 billion years old based on scientific evidence and geological understanding. Life on Earth originated around 3.5 to 4 billion years ago with the emergence of single-celled organisms.
Step-by-step explanation:
According to scientific evidence, Earth is approximately 4.5 billion years old. The age of Earth is estimated to be between 4.4 and 4.57 billion years old based on geological evidence and the age of the oldest rocks found on Earth. Life on Earth began around 3.5 to 4 billion years ago with the emergence of single-celled organisms similar to bacteria.