Space above mercury in a barometric tube has a water column of $$27.2\text{ cm}$$. If the atmospheric pressure is $$76\text{ cm}$$ of mercury, find the length of the mercury column above the mercury level in the trough of the barometer. What is the pressure at the top of the mercury column? Assume that space above water is vacuum. Atmospheric pressure is $$76\text{ cm}$$ of Hg and densities of mercury and water are $$13.6\text{ g/cm}^3$$ and $$1\text{ g/cm}^3$$.