Answer: D) Increase the sample size and decrease the confidence level.
Step-by-step explanation:
A reduced interval width means that the data is more accurate. This can only be achieved if the sample size is increased because a larger sample size is able to capture more of the characteristics of the variables being tested.
A smaller confidence interval will also lead to a reduced interval width because it means that the chances of the prediction being correct have increased.
Answer:
where ever your at looks dark.
Step-by-step explanation:
Answer:
The z-distribution should be used for this problem.
Step-by-step explanation:
The population distribution is assumed to be normal. Which distribution to use?
If we have the standard deviation for the sample, we use the t-distribution.
If we use the standard deviation for the population, we use the z-distribution.
There is a known standard deviation of 2.2 minutes.
This means that 2.2 is the population standard deviation, and thus, the z-distribution should be used for this problem.
Answer:
When we compare the significance level 
we see that 
so we can reject the null hypothesis at 10% of significance. So the the true mean is difference from 21 at this significance level.
Step-by-step explanation:
Data given and notation
represent the sample mean
represent the population standard deviation
sample size
represent the value that we want to test
represent the significance level for the hypothesis test.
z would represent the statistic (variable of interest)
represent the p value for the test (variable of interest)
State the null and alternative hypotheses.
We need to conduct a hypothesis in order to check if the average age of the evening students is significantly different from 21, the system of hypothesis would be:
Null hypothesis:
Alternative hypothesis:
The statistic is given by:
(1)
Calculate the statistic
We can replace in formula (1) the info given like this:
P-value
Since is a two sided test the p value would be:
Conclusion
When we compare the significance level we see that so we can reject the null hypothesis at 10% of significance. So the the true mean is difference from 21 at this significance level.
Answer:
5x-18=4x+7 ( vertical opposite angle)
5x-4x=7+18
x=25
