# Statistics Confidence Intervals Question?

1. Dec 5, 2013

### mintsnapple

1. The problem statement, all variables and given/known data
A Gallup Poll of 1002 adults in October 2002 found that 25% of the respondents said that their household
had experienced a crime in the past year. Among respondents aged 18-29 years, 43% had been victims of a
crime. Gallup says, “For results based on the total sample of national adults, one can say with 95%
confidence that the margin of sampling error is +/- 3 percentage points.” Is the margin of error for adults
aged 18-29 smaller than, larger than, or the same as +/- 3 percentage points?

2. Relevant equations

3. The attempt at a solution
Well, I think because of the smaller sample size, the margin of error would be larger because it is less precise. Yet, this sample size comes from a larger sample size with a given confidence interval width, so I am not sure.

2. Dec 6, 2013

### Ibix

Hi mintsapple!

Do you know how to calculate the confidence limit that Gallup provided? Can you calculate how big a sample of 18-24 year olds yu would need to get the same confidence interval?