How do scientists know about the structure of the earth? Question 21 options:

We have drilled all the way to the core of the earth.

We have drilled far enough into the earth to reach the mantle.

S waves from earthquakes can travel through both solids and liquids so they tell us what is inside the earth.

P waves from earthquakes can travel through both solids and liquids so they tell us what is inside the earth.

I think it's " P waves from earthquakes can travel through both solids and liquids so they tell us what is inside the earth.  "

Explanation:

Distance

Explanation:

The formula for average speed = d/t

= Distance / time

We already have the time to be given as = 30 seconds in this question

But the value for distance is not stated. Therefore the other information that is needed in this question in order for us to determine the average speed of this wheel is distance. I hope this answers your question.

Thank you!