Business Visa - B1

My parents attended visa interview along with my sister whose is B.Tech(IT) third year.Visa was approved .we were concerned whether she will get visa because of her age . But luckily they all got visa.
Thank you very much immihelp .com .I followed all the steps from your site for preparing documents and interview tips.

Following were the questions
1.what are you doing ?(for all 3)
 My dad gave his visiting card of his business
2 where do your daughters live?
    They mentioned both the places.(my other sister also lives in U.S.)
3.Who is your sponsor?
4.what other family do you have here?
  I have 3 daughters.Two of them are in US
5. Where is your other one?
 I am the third one(my sister answered)
6.Are your daughters US citizens?
7.what is there visa status?
8.How long are you planning to visit?
 1 month(looks at application and ask)
 why is it mentioned 2 months?
They said for back up
9 what do mean by back up?
I expected 2months leave in college
but got only a month.
10.what is the relationship of sponsor to you?
11.why are going to Us?
12.what is your monthly income?
13.Are you traveling together?
14.Is any one of you returning first?
no, we are returning together
15.where are you going first?
16.when are you going?
17.Have any one of you traveled out of country?
18.who is going to pay for the ticket?
19.which city are you going to go ?(mentioned 2 cities )
VO asked these questions by looking at application.NO documents was asked for reference.
Congratulation your visa is approved.