500g=0,5kg
ta có phương trình cân bằng nhiệt:
Q1+Q2=Q3
\(\Leftrightarrow m_1C_1\left(t_1-t\right)+m_2C_2\left(t_2-t\right)=m_3C_3\left(t-t_3\right)\)
\(\Leftrightarrow440\left(100-35\right)+8400\left(100-35\right)=4200m_3\left(35-20\right)\)
\(\Leftrightarrow28600+546000=63000m_3\)
\(\Rightarrow m_3\approx9,12kg\)