Why is 1/2 not useful as a benchmark to compare 5/8 and 9/10?

Solution:

1/2 is not a useful benchmark to compare 5/8 and 9/10 because if we observe closely we found that

and

In the first case 1/2 comes four times and in the second case 1/2 comes 5 times in multiplication so logically the second number 9/10 should be smaller than the first number 5/8.

But 9 is greater than 5 it mean second number should be greater than the first number.

Both the above two conclusions are contradictory to each other.

Hence we can not use 1/2 as a benchmark to compare 5/8 and 9/10.