Posted by **K.T** on Sunday, January 3, 2010 at 4:11pm.

the average of final exam is 64, the standard deviation is 7. If the teacher set a rule that 1/4 of students who receive the poor grades should stay after class. lower than what mark should the students stay in school?

does anyone know how to solve this?

- statistics -
**bobpursley**, Sunday, January 3, 2010 at 4:52pm
http://davidmlane.com/hyperstat/z_table.html

I get below 50.3

- statistics -
**K.T**, Sunday, January 3, 2010 at 4:57pm
my friend came out with the following solution.

P(Z<-0.675)=0.25

-0.675= (X-64)/7

but i'm kinda confused.

where did the 0.675 come from?

- statistics -
**bobpursley**, Sunday, January 3, 2010 at 8:39pm
Good question; ask your friend. It makes no sense. See the link I posted.

## Answer this Question

## Related Questions

- college - Suppose that, for a certain exam, a teacher grades on a curve. It is ...
- Statistics - In Professor Smith's statistics course, the correlation between ...
- statistics - In a large class, there were 220 students who wrote both the ...
- statistics - Percentage grades in a large physics class follow a normal ...
- Statisitics - In a large section of a Chemistry class, the points for the final ...
- Statistics - 1. The mean and standard deviation of the grades of a group of ...
- statistics - Suppose the final exam scores in a large class is symmetric mound ...
- statistics - In one history class, 34 students took an exam. The mean of the ...
- stats - Relatively speaking, which statistics exam did you do better on? On ...
- STATS - Suppose that the average weight of students in a statistics class is 75...

More Related Questions