The man released 1.8 MJ of heat into the water.
The equation that establishes a relationship between the heat absorbed by the water and the change in temperature looks like this
So, the first thing you need to do is determine the mass of water present in the tub. Since no mention of water's density was made, you can assume it to be equal to
This means that you have
A substance's specific heat tells you how much energy you need to supply to 1 gram of that substance in order to increase its temperature by
In water's case, you need 4.18 J to increase the temperature of 1 gram by
Plug your values into the equation and solve for
Rounded to two sig figs, the number of sig figs you gave for the two temperatures of the water, and aexpressed in megajoules, the answer will be