Question on specific heat capacity?

Question

The temperatures of three different liquids are maintained at 15, 20 and 25 degree celsius respectively.

When equal masses of the first two liquids are mixed, the final temperature is 18 degree celsius.

When eual masses of the last two liquids are mixed, the final temperature is 24 degress celcius. What temperature will be achieved by mixing equal masses of the first and last liquid?

you don't need to do the steps to show me. Just gimme the final answer. I seem to disagree with the answer scheme.

They are three different liquids with three different specific heat capacities.

Answer 1

1+2>>>>> 3c1=2c2

2+3>>>>> 4c2=c3 >>> c3=4*3/2 c1= 6c1

c's are specif heat capacities of 1.2.3

1+3>>>> c1(t - 15) = c3 (25 - t)
c1(t - 15) = 6c1 (25 - t)
t -15 = 150 - 6t
7 t = 165
t= 23.57 deg C

Answer 2

When they mix the first two (equal mass)-:

20 + 15 = 35
35 / 2 = 17.5 (or 18) - so that makes sense

The last two-:
20 + 25 = 45
45 / 2 = 22.5 (which should be 23 according to that)

So for the first and last-:
15 + 25 = 40
40 / 2 = 20 (that is what I would go for)

If the masses were different it would bring in slightly different equations of thermodynamics - it seems like the last liquid has a lower specific heat capacity than the middle liquid....(i.e. it needs less energy to raise the temperature by 1 degree)

Answer 3

energy = specific heat capacity * mass * temperature change

hope u benefit