A Camper Is About to Drink His Morning Coffee

A camper is about to drink his morning coffee.He pours 400 grams of coffee,initially at 75°C into a 250-g aluminum cup,initially at 16°C.What is the equilibrium temperature of the coffee-cup system,assuming no thermal energy exchange with the surroundings? The specific heat of aluminum is 900 J/kg ∙ K,and the specific heat of coffee is essentially the same as that of water,which is 4186 J/kg ∙ K.

A) 45°C
B) 62°C
C) 65°C
D) 68°C
E) 71°C