SOLUTION: Suppose that the average number of years to graduate at a university is 4 years, with a standard deviation of 0.5 years. Assume a bell-shaped distribution for years to graduate.

Question 311028: Suppose that the average number of years to graduate at a university is 4 years, with a standard deviation of 0.5 years. Assume a bell-shaped distribution for years to graduate.
From the Empirical Rule, what is a range of values that 95% of the students should graduate between?
From the Empirical Rule, what is a range of values that 68% of the students should graduate between?
From the Empirical Rule, what is a range of values that 99.7% of the students should graduate between?
Suppose that the average height for college men is 66 inches. If the height distribution is bell-shaped, and 95% of the men have heights between 60 inches and 72 inches, what is the standard deviation of heights for this population?
I know I am repeating but I am so confused!
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Suppose that the average number of years to graduate at a university is 4 years, with a standard deviation of 0.5 years. Assume a bell-shaped distribution for years to graduate.
From the Empirical Rule, what is a range of values that 95% of the students should graduate between?
Draw the picture.
4 yrs is in the middle
std = 1/2 yr
Empirical Rule says 95% of the population is within 2 std of the mean
2 std = 2(1/2) = 1
----
So 95% of the population graduate between 3 and 5 yrs.
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From the Empirical Rule, what is a range of values that 68% of the students should graduate between?
Same as above but population within 1 std.
68% between 3.5 and 4.5
===============================================================
From the Empirical Rule, what is a range of values that 99.7% of the students should graduate between?
Same as above but population within 3 std.
99.7% between 2.5 and 5.5 yrs.
===============================================================
Suppose that the average height for college men is 66 inches. If the height distribution is bell-shaped, and 95% of the men have heights between 60 inches and 72 inches, what is the standard deviation of heights for this population?
---
Draw the picture.
Normal curve; 4 in the middle; 95% centered on the mean.
Right end is 2 std above the mean.
Left end is 2 std below the mean.
Distance from mean to left end = 66-60 = 3
----
2std = (66-60)
2std = 6
std = 3
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Cheers,
Stan H.
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