Math 2600 Fall 2009 Quiz 2 Jason Stover
NAME
Suppose a data set x1, x2, ..., x400 has a sample mean of ¯xand sample standard deviation
s.
1. If ¯x= 40 and s= 10 find two values land uwith the property that at least 3/4 of
the data are between land u.
2. Now assume the data have a symmetric, bell-shaped distribution, and assume ¯x
and shave the values mentioned in the previous problem. Find two new values l
and usuch that about 95% of the data are between land u.
3. Again assume the data have a symmetric, bell shaped distribution, but that ¯xand
sare unknown. If the minimum value of the data is 10 and the maximum is 40,
approximately what is ¯x?
4. Using the information from the previous question, find an approximate value of s.