Grant has been invited by his friends to go skiing for the day. The cost of entry into the ski hill is $20 and Grant's contribution to travel costs is another $20. Grant's preferences are such that the benefit of skiing is worth $60 to him. He has a casual job as a research assistant for one of his professors. If Grant does not go skiing, he will spend the time working for his professor for the day. Grant likes this job well enough that he would be willing to do it for free. Grant's professor pays him $45 per day. If Grant is rational, will he choose to go skiing or will he choose to work? Explain