Answer:
6.8%
Explanation:
According to Stefan-Boltzmann law, radiation is directly proportional with temperature raised to the fourth power:
P ∝ T⁴
Writing a proportion:
P₁ / P₂ = T₁⁴ / T₂⁴
1.3P / P = (T₁ / T₂)⁴
T₁ / T₂ = ∜1.3
T₁ = 1.068 T₂
The temperature increased by 6.8%.
