Transcript Slide 1

State the null and alternative hypotheses in the
following case:
a) Experiments on learning in animals
sometimes measure how long it takes a
mouse to find its way through a maze. The
mean time is 20 seconds for one particular
maze. A researcher thinks that playing rap
music will cause the mice to complete the
maze faster. She measures how long each of
12 mice takes with the rap music as a
stimulus.
A student group claims that first-year students
at a university must study 2.5 hours per night
during the school week. A skeptic suspects
that they study less than that on the average. A
class survey finds that the average study time
claimed by 269 students is xbar = 137 minutes.
Regard these students as a random sample of
all first year students and suppose we know
that study times follow a Normal distribution
with standard deviation 65 minutes. What
conclusion would you draw?
A company that manufactures classroom chairs for high school students
claims that the mean breaking strength of the chairs they make is 300
pounds. From years of production, they have seen that σ=15 pounds.
One of the chairs collapsed beneath a 220 pound student last week.
You wonder whether the manufacturer exaggerated the breaking
strength of the chairs.
a) State the null and alternative hypotheses
b) Describe type 1 and type 11 error in this case. Which is more serious
What is the relationship between type 1 error and the significance
level?
What is the relationship between power and the P-value?
A researcher reports that the average salary of assistant
professors is more than $42,000. A sample of 30 assistant
professors has a mean salary of $43,260. At α = .05, test the
claim that assistant professors earn more than $42,000 a year.
The standard deviation of the population is $5230.
The medical Rehabilitation Education Foundation reports that the
average cost of rehabilitation for stroke victims is $24,672. To
see if the average cost of rehabilitation is different at a particular
hospital and finds that the average cost of their rehabilitation is
$25,226. The standard deviation of the population is $3251. At
α=.01, can it be concluded that the average cost of stroke
rehabilitation at a particular hospital is different from $24,672