Posted by **Alica** on Thursday, March 18, 2010 at 4:45am.

Final averages are typically approximately normally distributed with a mean of 65 and a standard deviation of 8. Your professor says that the top 10% of the class will receive an A; the next 20%, a B; the next 41%, a C; the next 19%, a D; and the bottom 10%, an F. (Give your answers correct to one decimal place.)

(a) What average must you exceed to obtain an A?

(b) What average must you exceed to receive a grade of C or better?

(c) What average must you obtain to pass the course? (You'll need a D or better.)

- Statistics 250 -
**drwls**, Thursday, March 18, 2010 at 11:33am
You need to learn how to use a normal probability distribution curve, or tables. There is one at

http://psych.colorado.edu/~mcclella/java/normal/accurateNormal.html

I used it to get the following answers:

(a) A score = 75.3 or better

(b) C score or higher (top 71%) = 60.8

(c) Passing D score or higher (top 90%) = 54.7

## Answer this Question

## Related Questions

- STAT 250 Probability - Final averages are typically approximately normally ...
- STAT 250 Probability - Final averages are typically approximately normally ...
- STATS HELP - Final averages are typically approximately normally distributed ...
- Statistic - Final averages are typically approximately normally distributed with...
- statistics - Professor Smith gave a final exam in her history class. The scores ...
- Analytical Skills - If your score on a statistics exam was 76 and the professor ...
- Statistics - X is normally distributed with a mean of 250 and a standard ...
- Statistics - A statistics professor gives a test and finds that the scores are ...
- statistics - A professor informs her class that a test is very difficult, but ...
- social science statistics - a professor was curious to whether the students in a...