Final answer:
For dating a rock, radiometric dating is more useful than relative dating as it provides a specific age in years, while relative dating only determines sequence without an exact age.
Step-by-step explanation:
A scientist determining the age of a rock can utilize two main methods: relative dating and absolute dating. Relative dating uses the sequence of rock layers to determine which fossils are older or younger but does not provide an age in years. However, if the rock contains an index fossil, which is a fossil known to have existed during a limited geological time range, it can be used for relative dating and to correlate the rock with other layers containing the same fossil.
The presence of an ancient relative of a livin organism in the rock can also assist with dating, but for precise dating, scientists would turn to radiometric dating, a form of absolute dating. This technique measures the decay rate of radioactive materials in the rock, giving a numerical age for the rock and the fossil it contains.
In conclusion, for dating a rock, absolute dating methods, like radiometric dating, are more useful because they provide a specific age in years. Whereas relative dating can only determine the sequence of events and is less precise in assigning an absolute age.