$5.00 stat (second)
- From Mathematics: Statistics
- Closed, but you can still post tutorials
- Due on Oct. 30, 2009
- Asked on Oct. 29, 2009 at 11:46:34AM
Q:
In 2001, the environmental protection agency of a particular state checked the underground gasoline storage tanks at all of the gasoline stations in the state and found that 40% of the gasoline stations in the state had at least one leaking gasoline storage tank. Note that a gasoline station generally has more than one storage tank. This agency then implemented a program to assist gasoline station owners in the repair of leaking storage tanks at their stations. In 2003, after this program had been in e®ect for two years, this agency checked the storage tanks at 175 gasoline stations, selected at random from all of the gasoline stations in the state, to determine whether the program had been successful and to estimate the extent to which the program reduced the problem of gasoline stations having leaking storage tanks. Among the 175 gasoline stations in the random sample mentioned above, 55 stations had at least one leaking storage tank in 2003.
a) For this example, what is a unit and what constitutes a \success"?
b) DeŻne a suitable population success proportion
p
. Be sure to describe the population
of units this proportion corresponds to.
c) State the appropriate research hypothesis, in terms of the proportion you deŻned in part
b), for deciding whether the data support the conclusion that the program implemented to
reduce the prevalence of leaking gasoline storage tanks was successful as of 2003. Brie°y
justify your choice of this hypothesis.
d) Perform a hypothesis test to see whether the data support the conclusion that the
program implemented to reduce the prevalence of leaking gasoline storage tanks was suc-
cessful as of 2003. Be sure to provide the
P
{value, and to provide your conclusions in
a brief summary statement in the context of this example.
Do not use the +2/+4
method to Żnd the
P
{value.
e) Construct a 95% conŻdence interval estimate for the proportion of gas stations with
leaking gasoline storage tanks in 2003 and provide a summary explaining your inference
about this proportion in the context of this example.
Use the +2/+4 method to Żnd
