probability and statistics
posted by kiera .
the average age for licensed drivers in the country is u=40.3 years with a standard deviation of o= 13.2 years.
a. a researcher obtained a random sample of n=16 parking tickets and computed an average age of m=38.9 years for the drivers. is it reasonable to conclude that this set of n=16 people is a representative sample of licensed drivers?
b. the same researcher obtained a random sample of n=36 speeding tickets and computed an average age of m=36.2 years for the drivers. compute the z-score for the sample mean and find the probability of obtaining an average age this young or younger for a random sample of licensed drivers. is it reasonable to conclude that this set of n= 36 people is a representative sample of licensed drivers?
Z = (mean1 - mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√n
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.