A tall cylinder contains 30 cm of water. Oil is carefully poured into the cylinder, where it floats on top of the water, until the total liquid depth is 40 cm. Part A What is the gauge pressure at the bottom of the cylinder

The gauge pressure is  

Explanation:

From the question we are told that

       The height of the water contained is  

        The height of liquid in the cylinder is  

At the bottom of the cylinder the gauge pressure is  mathematically represented as

Where   is the pressure of water which is mathematically represented as

Now   is the density of water with a constant values of  

   substituting values

While is the pressure of oil which is mathematically represented as

Where is the density of oil with a constant value

substituting values

Therefore