Express your answer in scientific notation. 1.8*10^-2 - 3.9*10^-3

Little’s law firm has just one lawyer. customers arrive randomly at an average rate of 6 per 8 hour workday. service times have a mean of 50 minutes and a standard deviation of 20 minutes. how long does a customer spend at little’s law firm on average?

Me i’m stuck on all these questions besides the two bottom ones

What is the surface area of a cube with the volume of 729 ft?