Answer:
about 30.714degC
Explanation:
Assuming
specific heat of water at 4200 J/kg * K
specific heat of aluminum 900 J/kg * K
(actual values to higher precision differ, and also change slightly with temperature).
To raise the aluminum's temp by 1K we need 900J * (210g / 1kg) = 189J
189J given by the water decreases its temp by 1K * (189J / 4200J) * (1kg / 550g) = 0.0(81)K.
So every K the temp of aluminum rises, 0.0(81)K falls the temp of the water.
At a difference of (32degC - 15degC) = 17K, we infer the temp will balance out after 17K / (1K + 0.0(81)K) "steps", so about 15.714.
The final temperature will be around 30.714degC
