(a) Do these data indicate that the population proportion of students in this school (ages 16-19) who have been victims of a crime is different (either way) from the national rate for this age group? Use
α = 0.05.
(i) What is the level of significance?
State the null and alternate hypotheses.
H
0:
p
= 0.10;
H
1:
p
> 0.10H
0:
p
= 0.10;
H
1:
p
≠ 0.10
H
0:
p
= 0.10;
H
1:
p
<>H
0: μ = 0.10;
H
1: μ > 0.10H
0: μ = 0.10;
H
1: μ ≠ 0.10H
0: μ = 0.10;
H
1: μ <>
(ii) What sampling distribution will you use? What assumptions are you making?
The Student's
t, since
np
< 5="">
nq
< 5.the="" standard="" normal,="">
np
< 5="">
nq
< 5. ="" the="" standard="" normal,="">
np
> 5 and
nq
> 5.The Student's
t, since
np
> 5 and
nq
> 5.
What is the value of the sample test statistic? (Round your answer to two decimal places.)
(iii) Find (or estimate) the
P-value.
P-value > 0.5000.250
P-value < 0.500 ="" 0.100="">
P-value < 0.2500.050="">
P-value < 0.1000.010="">
P-value <>P-value <>
Sketch the sampling distribution and show the area corresponding to the
P-value.
(iv) Based on your answers in parts (i) to (iii), will you reject or fail to reject the null hypothesis? Are the data statistically significant at level α?
At the α = 0.05 level, we reject the null hypothesis and conclude the data are statistically significant.At the α = 0.05 level, we reject the null hypothesis and conclude the data are not statistically significant. At the α = 0.05 level, we fail to reject the null hypothesis and conclude the data are statistically significant.At the α = 0.05 level, we fail to reject the null hypothesis and conclude the data are not statistically significant.
(v) Interpret your conclusion in the context of the application.
There is sufficient evidence at the 0.05 level to conclude that there is a difference from the national average for the population proportion of crime victims.There is insufficient evidence at the 0.05 level to conclude that there is a difference from the national average for the population proportion of crime victims.
(b) Find a 90% confidence interval for the proportion of students in this school (ages 16-19) who have been victims of a crime. (Round your answer to three decimal places.)
(c) How large a sample size should be used to be 95% sure that the sample proportion p̂ is within a margin of error
of the population proportion of all students in this school (ages 16-19) who have been victims of a crime?
. (Round your answer up to the nearest student.)