Advising on Heat Pump Efficiency for 1500J at 280K

[captainjack2000]

Homework Statement

The question asks us to advise the company on a heat pump (and give reasons) which is claimed to deliver 1500J to a room at 280K by consuming 50J of work per cycle pumping heat from the surroundings at 270K.
I've drawn a diagram of the heat pump, taking heat Q2 from a bath of 270K up to an engine/refrigerator into which goes work W=50J, from which heat Q1 goes into hot bath of 280K. I am a bit confused about what to do next.
Is it that the efficiency of a heat pump is = Q1/W = Q1/ (Q1-Q2) = ?

thanks

Homework Equations

The Attempt at a Solution

 

[Redbelly98]

It's actually referred to as "coefficient of performance" or COP, but yes that is the right idea.

Compare the claimed COP with what you'd get for a Carnot Cycle heat pump operating at those temperatures, to determine whether this COP is possible.