Answer:2:7
Step-by-step explanation:
Quantity of heat energy before mixing= Quantity of heat energy after mixing
M1. S1.T1+ M2.S2.T2= M.S3.T3
Let, .
M1 = mass of cold water
M2 = mass of hot water
S1=S2=S3=S
M=M1+M2
T1=28,T2=82,T3= 40
M1.28 + M2.82= (M1+M2)40
M1.28 + M2.82= M1 40+M2.40
M2.82 -M2.40= M2.40–M1.28
M2.42= M1. 12
M2/M1= 12/42= 2/7
Or
M2: M1= 2:7