statistical Conclusions

Question

1. A pet supply company wants to find out how satisfied their customers are with their service and inventory.
2. Assume that a survey was conducted of 500 people and 472 customers said that they were satisfied with the service.
3. 1. Find the percentage of people who were satisfied.
4. 2. Find the margin of error for the sample.
5. 3. Find the range of percentages of customers who were likely to be satisfied with their service.
6. 4. Use all of this information to write a statistical conclusion about the survey using complete sentences.

Answer 1

1). To find the % of people satisfies, simply calculate: [(# people satisfies)/ (total number of people)]*100=(471/500)*100=94.4%

2) To find the margin of error: since you have an N > 30, you should use the Z-score as the critical value. If you chose an α=0.05, the critical value is 1.94(look this value up in tables). Since you have statistics from a sample, you need to find the standard error of the sample. Once you have calculated these 2 values, you just need to multiple those 2 numbers to get the margin of error.

3)To find the range of percentage of customers who were likely to be satisfied: add and subtract the margin of error(answer you got for #2) from the percentage of people likely to be satisfied (94.4).

4)You need to do this part for yourself, but it would be something along the lines of:

You would expect the results to be within (the margin of error) percent of the 94.4 %

[(100-what you used for (α)] percent of the time.

In other words(if you chose α=0.05): 95% of the time you would expect the results to be between (94.4-SEM and 94.4+SEM).