Visitor Visa - B2

I'm Muhammad Salman from Karachi, Pakistan. Today(13-11-2015) my mom's B2 visa had been approved by US Consulate General Karachi. Interview was @ 7:45, and interview was in Urdu language. None of the supporting documents were asked by the VO. Interview was very simple and all the questions were asked from DS-160 application form.
VO was a male of age between 25-28

Following are the questions asked by VO:
1-VO: Assalam O Alaikum
Mom: Walaikum As-salam
2-VO: Why do you want to go to USA?
Mom: For tourism and to meet my brother.
3-VO: Where your brother reside in USA?
Mom: Woodbridge, Virginia.
4-VO: How many children do you have?
Mom: Eight(8).
5-VO: All are in karachi?
Mom: No my eldest daughter is in London and she is married.
6-VO: What your husband do to earn?
Mom: He's a Goldsmith.
7-VO: Where your husband do Goldsmith work?
Mom: In karachi's Saddar market.
8-VO: How much do you expect this trip cost?
Mom: Approximated 4,000 US$ to 5,000 US$

Then the golden words came your visa is approved. You can receive your passport within 3 working days.
Key Points:
1-Read the DS-160 form very carefully.
2-Answer should be simple and straight that the VO can understand.
3-Just be confident.
4-Explain the question "Why do you want to go to USA?" This is the question from where they can judge the candidates.