At the ridge, new crust forms by igneous intrusion and extrusion. Since hot rocks are in a more expanded state and then contract as they cool (as they spread away from the ridge), the midocean ridges stand up high above the surrounding seafloor. The seafloor depth increases with distance away from the midocean ridges.
You get 493.41 when
you subtract 15.54 from 508.953 using the rules for significant figures.
For addition
and subtraction, look at the decimal portion (i.e., to the right of the decimal
point) of the numbers ONLY. Here is what to do:
1) Count the
number of significant figures in the decimal portion of each number in the
problem. (The digits to the left of the decimal place are not used to determine
the number of decimal places in the final answer.)
2) Add or
subtract in the normal fashion.
3) Round the
answer to the LEAST number of places in the decimal portion of any number in
the problem.
The correct answer between all the choices given is the
third choice or letter C. I am hoping that this answer has satisfied your query
and it will be able to help you in your endeavor, and if you would like, feel
free to ask another question.
1/2 the wavelength.......
