Answer:
89.241 dB.
Step-by-step explanation:
dB is the unit of sound intensity and it stands for the word 'decibels'. The sound intensity can be represented mathematically with the formula in the equation (1) below;
H = 10 log (b/b°). ---------------------------(1).
Note that the logarithm is in base 10. Also, the b° is known as the hearing threshold. The hearing threshold, b° has the unit of W/m^2 and it has the mathematically value of 10^-12.
So, in the question we are given that one singer A produces 73.8 dB. 35 singers singing at the same intensity will produce a sound level of;
H = 10 log [35b/ b°].
H = 10 log 35 + 10 log [b/b°].
Where 10 log [b/b°] = 73.8 dB that is to say the sound level produced by one singer. So, we will have;
H= 10 log 35 + 73.8 dB.
H= 89.2406804435027563 dB.
H= 89.241 dB.