98. Let the initial water temperature be T

wi

and the initial thermometer temperature be T

ti

. Then, the

heat absorbed by the thermometer is equal (in magnitude) to the heat lost by the water:

c

t

m

t

(T

f

− T

ti

) = c

w

m

w

(T

wi

− T

f

) .

We solve for the initial temperature of the water:

T

wi

=

c

t

m

t

(T

f

− T

ti

)

c

w

m

w

+ T

f

=

(0.0550 kg)(0.837 kJ/kg

· K)(44.4 − 15.0) K

(4.18 kJ/kg

·C

◦

)(0.300 kg)

+ 44.4

◦

C

=

45.5

◦

C .