Assuming that the South Atlantic began forming 135 million years ago, and has been spreading steadily ever since, calculate the full seafloor spreading rate in cm/yr at the equator near Romanche Fracture zone (~3,500 km away from Africa).

The answer is 5.1852 cm/yr.

Explanation:

In order to calculate the full seafloor spreading rate in cm/yr, we have to first calculate the half-spreading rate which can be done by simply dividing the given distance (in cm) by time (yr); after calculating the half-spreading rate, we will double it and get the full seafloor spreading rate, thus:

Distance = 3,500 km = 3,500 * 100,000 cm = 350,000,000 cm

Time = 135,000,000 years

The half-spreading rate = distance : time = 350,000,000 : 135,000,000 = 2.5926 cm/yr.

Therefore, the full seafloor spreading rate = 2.5926 cm/yr * 2 = 5.1852 cm/yr.