Dec 2011 Q1 T CO

Dear sir ,
thank you firstly for your great teaching lectures
could you please help me in understanding the concept behind the relevant costs calculated regarding paragraph tow of the question ” the engineers’s cost
it said by the examiner that the relevant cost would be just the penalty of $500
while i see that there is no relevant costs here ,as their is one week ahead for the engineers to complete contract x and gain the contribution , so no need for penalty

thanks a lot