Answer:
49
Step-by-step explanation:
Answer:
D.
Step-by-step explanation:
For this case we have the following equation:

Where,
I: <span>the intensity of a given sound
I0: </span><span> the threshold of a hearing intensity
</span>Substituting values in the given equation we have:
<span />

<span />Rewriting the equation we have:
<span />

<span />Then, by properties of logarithm we have:
<span />

<span />Finally we have:
<span />

<span />
Answer:
T<span />
he intensity, in decibles, [I(dB)], when I=10^8(I0) is:
D.80
V1=50km/h
v2=90km/h
s1=s2=6km
s=12km
The average speed over the 12 km drive:
v=s/t
The time needed to drive 12km will be:
t = t1+t2
t1=s1/v1, t2=s2/v2
t=s1/v1+s2/v2=(s1v2+s2v1)/(v1v2)
v=sv1v2/(s1v2+s2v1)=12*50*90/(6*50+6*90)=64,28 km/h