Need Help On Random Samples PLeaseeee?

Question

According to the national restaurant association, 20% of fine-dining restaurants have instituted policies restricting the use of cell phones. If you select a random sample of 100 fine-dining restaurants

a)What is the probability that the sample has between 15% and 25% that have established policies restricting cell phone use?
b)The probability is 90% that the sample percentage will be contained within what symmetrical limits of the population percentage?
c)The probability is 95% that the sample percentage will be contained within what summetrical limits of the population percentage


If someone can explain this to me since i havent been in class i injured my leg during a football game and couldnt walk please help me

Answer 1

Were the samples the NRA took random? How did they define "fine-dining?" OK First, 1/5 of the restaurants had the policy. If it was random, and if you select the same type of restaurant as defined by their parameters, and if they didn't massage the numbers too much, the chances are 100% that 20 of your 100 will have the same type of policy. The easiest way to check, is to do your own survey, or do a null-hypothesis. Check your book for Pierson or Fisher formulae for checking results. Wish I could help more, but it's been almost 15 years, and I barely made it in stats. You could always call your prof. or the study skills center at your school.

Answer 2

the perfect technique is stratified sampling the position, for this reason, the inhabitants is stratified by ability of age and easy random samples are received from the strata. this isn't between the options, so c) might want to be the anticipated answer, i imagine.