I'm horrible at Math,someone help me.

Question

You add 800 mL of water at 20C to 800 mL of water at 80C. What is the most likely final temperature of the mixture?
A. 60C

B. 50C

C. 25C

D. 100C

Answer 1

The answer is (B) 50C

 

_{you can calculate from the formula:}

 

q = (mass) (Δt) (C_p)

Δt is change in temperature

 

q_lost = q_gain

Lets X is the final temperature of water after mixing, then 

 

(800/D) (80-X) (C_p) = (800/D) (X-20) (C_p)

 

here D is density of water, C_p is specfic heat of water

 

by solving, you get :

 

(80-X) = (X-20)

 

2X = 100

 

X = 50 C