The alignment of the moon, the sun and earth to cause a spring tide

Spring tides occur when the Earth, sun and moon are aligned. Despite its name spring tides have nothing to do with the Spring season. It was derived from the concept of "springing-forth" . They occur at twice each lunar month, bringing higher tides during high tide and lower tides during low tide. 

20: 5

explanation:

about 20% of the world's population lives in   southwest asia, but on less than 5% of the world's   land area.