Posted by **Anonymous** on Tuesday, May 21, 2013 at 8:46pm.

a study shown that 20% of all college textbooks cost at least $70.it is known that the standard deviation of the prices of all college textbook is $9.50.assuming that prices of all college textbooks follow a normal distribution, find the mean price of all college textbooks.

- final exam -
**bobpursley**, Tuesday, May 21, 2013 at 8:56pm
http://www.jiskha.com/display.cgi?id=1369182329

Put in this applet the standard deviation, then the mean as zero.

Then start at -6, check the area. EVentually, you will get an area of .20

Then, say -6.5 is the point, you know that is really 70, so add 70 +6.5, and you have the mean.

## Answer this Question

## Related Questions

- Engineering Statistics - "A study has shown that 20% of all college textbooks ...
- math - A study has shown that 20.05% of all college textbooks have a price of $...
- statistics - A sample of the number of study per week of college students is ...
- Statistics - The standard deviation of GPAs (grade point averages) of all male ...
- statistics - Describe whether the following study would most likely be “...
- Statistics - In Professor Smith's statistics course, the correlation between ...
- Statistics - I am not sure how to even get started on this question could ...
- statistics - A maker has the opportunity to purchase several acres of land that ...
- statistics - At a small college it is known from previous years that 35% of all ...
- math - random sample of 9600 students. 46% had at least one parent who was a ...