Ocean trenches are formed when
a) two oceanic plates slide past each other.
b) an oceanic plate goes under another oceanic plate.
c) two oceanic plates grind past each other along transform faults.
d) two oceanic plates hit each other causing both plates to rise up.

At an oceanside nuclear power plant, seawater is used as part of the cooling system. this raises the temperature of the water that is discharged back into the ocean. the amount that the water temperature is raised has a uniform distribution over the interval from 10° to 25° c. what is the standard deviation of the temperature increase?