In: Statistics and Probability
Researchers interviewed street prostitutes in Canada and the
United States. The mean age of the 100 Canadian prostitutes upon
entering prostitution was 18 with a standard deviation of six. The
mean age of the 130 United States prostitutes upon entering
prostitution was 20 with a standard deviation of eight. Is the mean
age of entering prostitution in Canada lower than the mean age in
the United States? Test at a 1% significance level.
NOTE: If you are using a Student's t-distribution for the
problem, including for paired data, you may assume that the
underlying population is normally distributed. (In general, you
must first prove that assumption, though.)
Part (a)
State the null hypothesis.H0: μC ≠ μUS
H0: μC = μUS
H0: μC < μUS
H0: μC > μUS
Part (b)
State the alternative hypothesis.Ha: μC > μUS
Ha: μC = μUS
Ha: μC ≠ μUS
Ha: μC < μUS
Part (c)
In words, state what your random variableXC − XUS
represents.XC − XUS
represents the mean difference in the age of entering prostitution in Canada and the United States.XC − XUS
represents the mean age of entering prostitution in Canada and the United States.XC − XUS
represents the difference in the ages of entering prostitution in Canada and the United States.XC − XUS
represents the difference in the mean age of entering prostitution in Canada and the United States.Part (d)
State the distribution to use for the test. (Enter your answer in the form z or tdf where df is the degrees of freedom. Round your answer to two decimal places.)Part (e)
What is the test statistic? (If using the z
distribution round your answer to two decimal places, and if using
the t distribution round your answer to three decimal
places.)
---Select--- z t =
Part (f)
What is the p-value?p-value < 0.0100.010 < p-value < 0.050 0.050 < p-value < 0.100p-value > 0.100
H0
is false, then there is a chance equal to the p-value that the sample mean age of entering prostitution in Canada is at least 2 more than the sample mean age of entering prostitution in the United States.IfH0
is true, then there is a chance equal to the p-value that the sample mean age of entering prostitution in Canada is at least 2 less than the sample mean age of entering prostitution in the United States. IfH0
is true, then there is a chance equal to the p-value that the sample mean age of entering prostitution in Canada is at least 2 more than the sample mean age of entering prostitution in the United States.IfH0
is false, then there is a chance equal to the p-value that the sample mean age of entering prostitution in Canada is at least 2 less than the sample mean age of entering prostitution in the United States.Part (g)
Sketch a picture of this situation. Label and scale the horizontal axis and shade the region(s) corresponding to the p-value.Part (h)
Indicate the correct decision ("reject" or "do not reject" the null hypothesis), the reason for it, and write an appropriate conclusion.(i) Alpha (Enter an exact number as an integer, fraction, or decimal.)reject the null hypothesisdo not reject the null hypothesis
Since p-value < α, we do not reject the null hypothesis.Since p-value > α, we do not reject the null hypothesis. Since p-value > α, we reject the null hypothesis.Since p-value < α, we reject the null hypothesis.
There is sufficient evidence to show that the mean age of entering prostitution in Canada is lower than the mean age in the United States.There is not sufficient evidence to show that the mean age of entering prostitution in Canada is lower than the mean age in the United States.
Part (i)
Explain how you determined which distribution to use.The standard normal distribution will be used because the samples involve the difference in proportions.The t-distribution will be used because the samples are dependent. The standard normal distribution will be used because the samples are independent and the population standard deviation is known.The t-distribution will be used because the samples are independent and the population standard deviation is not known.
Part (a)
State the null hypothesis
H0: μC = μUS
Part (b)
State the alternative hypothesis.
Ha: μC < μUS
Part (c)
In words, state what your random variable
XC − XUS
represents
XC − XUS
represents the mean difference in the age of entering prostitution in Canada and the United States.
Part (d)
State the distribution to use for the test.
t -distribution with df = 228
Part (e)
What is the test statistic?
Part (f)
What is the p-value?
P-value =0.0189
Part (g)
Sketch a picture of this situation.
Part (h)
Indicate the correct decision ("reject" or "do not reject" the
null hypothesis), the reason for it, and write an appropriate
conclusion.(i) Alpha (Enter an exact number as an integer,
fraction, or decimal.)
α = 0.01
(ii) Decision:
do not reject the null hypothesis .
(iii) Reason for decision:
.Since p-value > α, we do not reject the null hypothesis.
(iv) Conclusion:
There is not sufficient evidence to show that the mean age of entering prostitution in Canada is lower than the mean age in the United States.
Part (i)
Explain how you determined which distribution to use.
The t-distribution will be used because the samples are independent and the population standard deviation is not known.
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