Increasing of sample size will decrease the width of the confidence intervals because it also decreases the standard error of the interval. So whenever the 'sample size' is increases then the 'confidence interval' decreases as well as the 'error' decreases.
Confidence interval gives us the unknown average population or percentage of the population. This gives us just how much the average rate is varying. Confidence interval gives the location as well as the precision of a measure. The smaller sample sizes gives more wider intervals.
