Answer:
(a). The total sound intensity
.
(b). The combined sound level 76.19 dB.
Explanation:
Given that,
Sound level = 75.0 dB
We need to calculate the noise
Using formula of intensity

Put the value into the formula


We need to calculate the sound intensity


(a). We need to calculate the total sound intensity
The total sound intensity



(b). We need to calculate the combined sound level
Using formula of sound level



Hence, (a). The total sound intensity
.
(b). The combined sound level 76.19 dB.