A student wants to estimate the mean score of all college st

A student wants to estimate the mean score of all college students for a particular exam. First use the range rule of thumb to make a rough estimate of the standard deviation of these scores. Possible scores range from 800 to 2200. Use technology and the estimated standard deviation to determine the sample size corresponding to a 99% confidence level and a margin of error of 100 points. What isn\'t quite right with this exercise?

Solution

a)

The range rule tells us that the standard deviation of a sample is approximately equal to one fourth of the range of the data. In other words s = (Maximum – Minimum)/4. This is a very straightforward formula to use, and should only be used as a very rough estimate of the standard deviation.

the estimated range is (2200-800)/4=1400/4=350

b) the sample require atlest

350*(2.58)/sqrt(n) = 100

then by solving for n we get n=82

c)

the range rule of thumb introduces too much inaccuracy for this proccedure