Question

- In a population, u = 100 and s
_{x}= 25. A sample of 150 people has a mean of 120.- Using two tails and a criterion of .05, what is the critical value?

- Compute standard error of the mean
(
*σ**X**)*and*z*-score of the sample mean. Show your work.

- Is the sample mean in the region of rejection and how do you know? (Hint: draw it out)

- Should we conclude that this sample is representative of the population? Why or why not?

Answer #1

suppose a random sample of 25 is taken from a population that
follows a normal distribution with unknown mean and a known
variance of 144. Provide the null and alternative hypothesis
necessary to determine if there is evidence that the mean of the
population is greater than 100. Using the sample mean ybar as the
test statistic and a rejection region of the form {ybar>k} find
the value of k so that alpha=.15 Using the sample mean ybar as the...

A sample of n = 16 individuals is selected from a population
with µ = 30. After a treatment is administered to the individuals,
the sample mean is found to be M = 33. We do not know the
population standard deviation.
A. If the sample variance is
s2 = 16, then calculate the estimated standard
error and determine whether the sample is sufficient to conclude
that the treatment has a significant effect? Use a two-tailed test
with α =...

A sample of n = 16 individuals is selected from a population
with µ = 30. After a treatment is administered to the individuals,
the sample mean is found to be M = 33. We do not know the
population standard deviation.
A. If the sample variance is
s2 = 16, then calculate the estimated standard
error and determine whether the sample is sufficient to conclude
that the treatment has a significant effect? Use a two-tailed test
with α =...

Suppose that we will randomly select a sample of 79 measurements
from a population having a mean equal to 21 and a standard
deviation equal to 8. (a) Describe the shape of the sampling
distribution of the sample mean . Do we need to make any
assumptions about the shape of the population? Why or why not?
Normally distributed ; yes , because the sample size is large . (b)
Find the mean and the standard deviation of the sampling...

Consider the following hypothesis test: H0: u = 15 Ha: u ≠
15
A sample of 40 provided a sample mean of 14.17. The population
standard deviation is 5. Enter negative value as negative
number.
a. Compute the value of the test statistic (to 2 decimals).
b. What is the p-value (to 4 decimals)?
c. Using , can it be concluded that the
population mean is not equal to 15?
answer the next questions using the critical value approach.
d....

1. An unstandardized test of aggression has a mean of 35.19. You
take a sample of 44 video game players and find their scores on
this test have a mean of 39.84 and a standard deviation of 12.42.
Are their aggression scores greater than the standard of 35.19?
a. State the null and alternative hypotheses.
b. Find your critical value(s) with a criterion of .01. Remember
if the appropriate line is not available exactly in the table to
pick the...

Questions 21-28: Does consuming sports energy drinks
improve endurance? For the general population, scores on an
endurance task have a mean of 50 with a standard deviation of 12. A
sample of 50 students is given energy drinks and their mean
performance on the endurance task is 53. Use an alpha level of
0.01
21. Using symbols state the null hypothesis
22. Using symbols state the alternative hypothesis
23. Is this a one-tailed or two tailed test?
24. Where would...

a sample is randomly selected from a population with a
mean of u =50 and a treatment is administered to the individuals in
the sample after treatment the sample is found to have a M= 56 with
a standard deviation of s= 8 if there are n = 4 individuals in the
sample, are the data sufficient to reject Ho and conclude that the
treatment has a significant effect using a two-tailed test with a=
.05
(use/round to 3 decimal...

Ok, let’s say there’s about 10 calories per ounce of human blood
and let’s assume that vampires have the same daily caloric need as
humans: 2,000 calories per day. This would mean that vampires would
need about 200 ounces, or 12.50 pints, of human blood per day. This
would require the vampire to fully exsanguinate about on 1.5 adult
humans per day (night?)!
Luckily for us mortals, it turns out that vampires need less
than 2,000 calories per day (they...

A researcher asks a large population of people (several
thousand) how many times per year they attend religious services.
The mean number is 17 and the standard deviation is 7. You recruit
a random sample of 144 people and ask them the same question. The
mean for the sample is 17.75. First, compute the standard error of
the mean. Next, conduct a z test and use Table Z to find the area
of the normal curve that falls beyond the...

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