Using the scale provided, measure the distance in kilometers from ridge axis to the beginning (right edge) of the yellowish normal polarity stripe for each ridge. How many kilometers has each side of these ocean basins spread during the past 1 million years

152.4 km each side of these ocean basins spread during the past 1 million years.

Explanation:

The mid Atlantic ridge is spreading at a very fast rate and its due to the spreading of lavas on the either side of the oceanic plate it continues to expand, the ocean spread at a speed of 3-6 inches in a year and thus the  axis to the beginning of the yellowish polarity.

Magma is outside the volcano  and lava is inside the volcano.