The first inequality is false:

Mainly because 9/10 is less than 1, and 8/5 is greater than 1.
The second inequality is false:

Because 6/5 is greater than 1.
The third inequality is false:

Because these numbers are equal to 2.5.
The fourth inequality is true:

Because 8/4 is equal to 2, which is less than 5.