Question

Some researchers claim that herbal supplements improve human
memory. To test this claim, a researcher selects a sample of n = 25
college students. Each student is given herbal supplements daily
for 6 weeks and then all the participants are given a standardized
memory test. For the population, scores on the tests are normally
distributed with µ = 70 and σ= 20. The sample of n = 25 students
had a mean score of M = 80. Can we conclude that the memory scores
of the sample after the “herbal supplement” treatment are
significantly greater than those of the general
population(population mean before treatment)? **Perform a
hypothesis test using a z- score statistic. Use a one-tailed test
with α = .05**.

The critical z-value is

Answer #1

Some researchers claim that herbal supplements improve human
memory. To test this claim, a researcher selects a sample of n = 25
college students. Each student is given herbal supplements daily
for 6 weeks and then all the participants are given a standardized
memory test. For the population, scores on the tests are normally
distributed with µ = 70 and σ= 15. The sample of n = 25 students
had a mean score of M = 75. Can we conclude...

Some researchers claim that herbal supplements such as ginseng
or ginkgo biloba enhance human memory. To test this claim, a
researcher selects a sample of n = 25 college students. Each
student is given a ginkgo biloba supplement daily for six weeks and
then all the participants are given a standardized memory test. For
the population, scores on the test are normally distributed with m
= 70 and s = 15. The sample of n = 25 students had a...

Some researchers claim that herbal supplements like ginseng
enhance human memory. To test this claim, a researcher selects a
sample of n=30 college students. Each student is given a
ginseng supplement daily for six weeks and then all of the
participants are given a standard memory test. For the population,
scores on the test are normally distributed with μ=80 and σ=20. The
sample of n=30 students had a mean memory score of
M=85.
a) Are these data sufficient to show...

Some researchers claim that herbal supplements such as ginseng
or ginkgo biloba enhance human memory. To test this claim, a
researcher selects a sample of n = 28 college students. Each
student is given a ginkgo biloba supplement daily for 6 weeks and
then all of the participants are given a standardized memory test.
Scores on the standardized test are μ = 80 and standard
deviation of 15. The sample of 28 students had a mean score of M =...

Some researchers claim that herbal supplements such as ginseng
or ginkgo biloba enhance human memory. To test this claim, a
researcher selects a sample of n = 28 college students. Each
student is given a ginkgo biloba supplement daily for 6 weeks and
then all of the participants are given a standardized memory test.
Scores on the standardized test are μ = 80 and standard deviation
of 15. The sample of 28 students had a mean score of M =...

A researcher is testing the effectiveness of a new herbal
supplement that claims to improve memory performance. A
sample of n = 25 college students is obtained and each student
takes the supplement daily for six week. At the end of
the 6-week period, each student is given a standardized memory test
and the average score for the sample is M = 39. For the
general population of college students, the distribution of test
scores is normal with a mean of µ =...

Research has claimed that sleeping 10 hours a night will enhance
human memory. To test this claim, a researcher selects a sample of
n=25 college students. Each of the 25 students is allowed to sleep
10 hours every night in a sleep lab for 4 weeks. All of the
participants are given a standardized memory test after the 4 week
period. For the population, scores on the standardized memory test
are normally distributed with a μ = 70 and σ...

Many people take ginkgo supplements advertised to improve
memory. Are these over-the-counter supplements effective? In a
study reported in the paper “Ginkgo for memory Enhancement”
(Journal of the American Medical Association), elderly
adults were assigned at random to either a treatment or a control
group. The 104 participants who were assigned to the treatment
group took 40 mg of ginkgo three times a day for six weeks. The 115
participants assigned to the control group took a placebo pill
three...

Suppose that memory for unrelated words is distributed normally
with a mean of µ = 50 with a standard deviation of σ = 12. A random
sample is selected from this population. After a treatment is
administered to the individuals in the sample, a memory test that
measures memory for unrelated words is administered, the sample
mean is found to be M = 55.
If the sample consists of n = 16 scores, can we
conclude that the treatment has...

A researcher selects a sample of n = 100 from a normal
population with µ = 50 and σ = 30. If the
treatment is expected to decrease scores by 10 points, what is the
power of a two-tailed hypothesis test using α = .05?

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