How should molecular clocks be used if not all mutations occur at the same rate?

Hybrid instruments that play sounds that are part sampled and part synthesized are known as:

A60-tooth gear is connected to a 72-tooth gear.if the smaller gear turns 12 times,how many turns does the larger gear make?

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.