I'm having trouble with this question. I can do part (a) but i don't no where to start on question (b) and (c). Can anyone help me?

In a quality assurance study, 10 bottles of lemonade, each nominally containing 1 litre, are selected and the true volume of lemonade contained in each is measured.
The results, in mls, are
997; 1003; 999; 988; 1006;
1005; 1007; 1009; 994; 1002:

(a) Calculate the sample mean and sample standard deviation for these measurements.

(b) Construct the 99% confidence interval for the true mean using a distribution appropriate for this small sample.

(c) A further study is undertaken, in which 150 sample bottles are used. The sample mean and standard deviation are found to be x = 998 and s = 4 respectively.
Using an appropriate distribution, calculate the 99% confidence interval for the true mean.

Any help would be appreciated, thanks.