You need to know the area if you're going to
1st selection: cover the surface of the dartboard.
No it is not a function. tell me if you need explanation
Part a)
The simple random sample of size n=36 is obtained from a population with

and

The sampling distribution of the sample means has a mean that is equal to mean of the population the sample has been drawn from.
Therefore the sampling distribution has a mean of

The standard error of the means becomes the standard deviation of the sampling distribution.

Part b) We want to find

We need to convert to z-score.

Part c)
We want to find

We convert to z-score and use the normal distribution table to find the corresponding area.

Part d)
We want to find :

We convert to z-scores and again use the standard normal distribution table.

Angle C, it sounds obvious but they correspond to the angle in the same order as them, as both E and C are in the middle it has to be C.