Answer: d. None of the above are correct.
Step-by-step explanation: Noise is a superfluous random alteration in an eletrical signal. There are different types of noises created by different devices and process. Thermal noise is one of them. It is unavoidable because is created by the agitation of the charge carriers, due to temperature, inside an eletrical conductor at equilibrium and is present in all eletrical circuits.
The formula to find the thermal noise power (N) is: N =
.T.B, where:
is Boltzmann constant (1.38.
J/K);
T is temperature in Kelvin;
B is the bandwith;
Calculating the thermal noise power:
N = 1.38.
·292·40
N = 16118.4.
dBm
The thermal noise power [N] = 16118.4.
dBm
Noise power density or simply Noise density (N₀) is the noise power per unit of bandwith and its SI is watts per hertz.
For thermal noise, N₀ = kT, where
<em>k </em>is the Boltzmann constant in J/K;
T is the receiver system noise temperature in K;
N₀ = 1.38.
. 292
N₀ = 402.96.
W/Hz
The thermal noise power density [N₀] = 402.96.
W/Hz
Answer: Choice D) 
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Work Shown:

Explanation:
First I subtracted y/b from both sides. Then I multiplied both sides by 'a' to fully isolate x. You can optionally distribute the 'a' through to each term inside the parenthesis, but your teacher has chosen not to do this.
Step-by-step explanation:
(30 men, 56 days, 6 hours daily)
=> (30 men, 48 days, 7 hours daily)
=> (45 men, 32 days, 7 hours daily)
Hence it will take 32 days.
Answer:
r≈23.4cm
Step-by-step explanation: