failed exam on sampling..can you help?

Hi

I failed my data analysis exam and this question was one of many that I got wrong..

A 2% random sample of mail-order customers, each with a numeric serial number, is to be selected. A random number between 00 and 49 is chosen and turns out to be 14. Then customers with serial numbers 014, 064, 114, 164, 214 … are chosen as the sample.

(a)State the sampling frame for this survey.

(b)Name the type of sampling described above.

(c)Give one advantage and one disadvantage of this method of sampling.

(d)Explain why the random number ‘14’ was chosen first.

Would be nice to know where i went wrong, can anyone answer this for me so i can compare my notes?