A container holds a 0.40m layer of oil (density 800kg/m3) floating on top of a 0.60m layer of water (density 1000kg/m3). The container is open to the atmosphere. What is the gauge pressure at the bottom of the container?
a) 5.9×103Pa
b) 3.1×103Pa
c) 9.0×103Pa
d) 7.8×103Pa