What is the geometric mean of 2/3 and 27/40 and how do u find it?

The geometric mean of two non negative numbers x and y is √(xy). (mean square root of XY)

So the geometric mean of 2/3 and 27/40 is

√(2/3 * 27/40)
= √(54 / 120)
= √(27 / 60)
= √(9 / 20)
= 3 / √20
= 3 / 2√5
= 3√5 / 10.