Hey, Melany. To answer this problem, simply set up a proportion: . Now let's solve for x.
- Cross multiply:
- Isolate x:
This means that x = 24.
There are 24 9th graders in the band.
31. The director of a marketing department wants to estimate the proportion of people who purchase a certain product online. The
1 answer:
You might be interested in
There is a relationship between confidence interval and standard deviation:
Where
is the mean, 
is standard deviation, and n is number of data points.
Every confidence interval has associated z value. This can be found online.
We need to find the standard deviation first:
When we do all the calculations we find that:
Now we can find confidence intervals:
We can see that as confidence interval increases so does the error margin. Z values accociated with each confidence intreval also get bigger as confidence interval increases.
Here is the link to the spreadsheet with standard deviation calculation:
https://docs.google.com/spreadsheets/d/1pnsJIrM_lmQKAGRJvduiHzjg9mYvLgpsCqCoGYvR5Us/edit?usp=sharing
Where
Every confidence interval has associated z value. This can be found online.
We need to find the standard deviation first:
When we do all the calculations we find that:
Now we can find confidence intervals:
We can see that as confidence interval increases so does the error margin. Z values accociated with each confidence intreval also get bigger as confidence interval increases.
Here is the link to the spreadsheet with standard deviation calculation:
https://docs.google.com/spreadsheets/d/1pnsJIrM_lmQKAGRJvduiHzjg9mYvLgpsCqCoGYvR5Us/edit?usp=sharing