The normal distribution curve for the problem is shown below
We need to standardise the value X=405.5 by using the formula


We now need to find the probability of z=0.32 by reading the z-table
Note that z-table would give the reading to the left of z-score, so if your aim is to work out the area to the right of a z-score, then you'd need to do:

from the z-table, the reading

gives 0.6255
hence,

The probability that the mean weight for a sample of 40 trout exceeds 405.5 gram is 0.3475 = 34.75%
Answer:
x=1
Step-by-step explanation:
So, first you make sure to multiply the parenthesis by the negative so then it would be,
-x-3=2x-6
Then you add the -3 from the right to the other side
so, -x=2x-3
Then you want all the X variables to one side so you subtract the 2x to both sides.
so, -3x=-3
divide both by -3
x=1
-π/2 < arctan(x) < π/2
So cos(π/2) < cos(arctan(x)) < cos(0)
0 < cos(arctan(x)) < 1