The answer for 2 is 320 because you have to keep counting by 40's
We all know about the bell curve i.e. normal distribution curve. It is centered about the mean and spread equally on each side.
We describe the area of the curve with the help of standard deviations.
With in 1 standard deviation about the mean i.e. from -1 s.d. (left of mean) to +1 s.d. (right of mean), it covers 68% of the total area of curve.
So, the data that falls outside 1 standard deviation of the mean would be equal to (100% - 68%) i.e. 32%.
So, 32% is the final answer.
We have the given I = 10^-1 and I₀ = 10^-12.
Simply plugging in the values to the equation, we have:
L = 10log(10^-1/10^-12)
L = 110 Db
The answer is D.
(I used a scientific calculator in solving for L).
The correct answer is X=6
I think the answer is 1/2. C.