Mean and Standard Deviation of a Sample Distribution

Hi!! I'm currently studying for a statistics midterm tmrw, and am stuck on a particular set of questions.. If anyone could please help, I'd really appreciate it!

The question asks:

If we were to take samples of 12 people from our class data, and use their heights,

a. What would the mean of the sampling distribution (distribution of sample means) be?
b. What is the standard deviation of this distribution?
c. What is the likelihood of getting a sample (n=12) with a mean height of 173cm or taller?

In an earlier question, we were asked:

If you take samples of 16 digits from the random number table, what will be the mean and standard deviation of the distribution of sample means.

Since there are a possibility of 10 digits in the random number table (0-9), and there is a .1 probability of getting each number, I calculated the mean for the population:

= 0(.1)+1(.1)+2(.1)+3(.1)+4(.1)+5(.1)+6(.1)+7(.1)+8(.1)+9(.1)
=4.5

I then calculated the standard deviation for the population:

= 2.87

We know that the population mean = the sample mean, so = 4.5..
And standard deviation is divided by the square root of n (16=4)..
= 2.87/4
= 0.72

I just wanted to make sure I did it right, and I'm confused how to use this method for the first question I asked? Please help!

Sadly:
1) You did not share your data.
2) You did not demonstrate the calculation of any Standard Deviation

Other than that, it looks good enough.