Worksheetsprop z tests and ints
Total questions: 16
Worksheet time: 48mins
Lumber companies dry freshly cut wood in kilns before selling it. A certain percentage of boards develop cracks on their ends during drying. The current drying procedure is known to produce cracks in 16% of boards. The drying supervisor wants to try a new method that she believes will result in a proportion of cracked boards that is less than 16%.
Write the appropriate hypotheses.
Ho: p = 0.16
Ha: p = 0.16
Ho: p = 0.16
Ha: p =/= 0.16
Ho: p = 0.16
Ha: p > 0.16
Ho: p = 0.16
Ha: p < 0.16
The drying supervisor uses the new method on a random sample of 200 boards. She conducts a hypothesis test on her sample data and gets a p-value of .027. Based on the p-value , was there convincing evidence that the new method is better? Use α = 0.05.
Since our p-value of 0.027 is < α , we reject the null hypothesis. We have convincing evidence that the new method is better.
Since our p-value of 0.027 is >undefined , we fail to reject the null hypothesis. We do not have convincing evidence that the new method is better.
At the end of the current growing season, the quality inspector took a sample of 50 pineapples and conducted a hypothesis test on the sample data. His test produced a p-value of 0.1317. Based on the p-value, was there convincing evidence that the current pineapples are larger? Use α =0.05.
Since our p-value of 0.1317 is < α , we reject the null hypothesis. We have convincing evidence that the pineapples are larger.
Since our p-value of 0.1317 is >undefined , we fail to reject the null hypothesis. We do not have convincing evidence that the pineapples are larger.
Suppose the P-value for a hypothesis test is 0.0304. Using a = 0.05, what is the appropriate conclusion?
a) Reject the null hypothesis
b) Reject the alternative hypothesis
c) Fail to reject the null hypothesis
d) Fail to reject the alternative hypothesis
When p-value is greater than alpha (we use 0.05) we:
Reject Ho
Fail to reject Ha
Fail to reject Ho
Reject Ha
You perform a One-Proportion z-test on your calculator and get a p-value of 0.05121. What do you do?
Reject the null
Fail to reject the null
You perform a One-Proportion z-test on your calculator and get a p-value of 0.04999. What do you do?
Reject the null
Fail to reject the null
What is the margin of error for the interval (6.8, 12.9)?
9.85
3.05
3.50
6.8
In a survey of 104 students, it was found that 79 went to the homecoming game this year.
A 99% confidence interval for p is (0.652, 0.868). Interpret this interval.
99% of the time the true proportion of people who went to the homecoming game this year is between 65.2% and 86.6%.
The probability that the population proportion of people who went to the homecoming game this year is between 65.2% and 86.6% is 95%.
Based on this sample, I am 99% confident that the true proportion of people who went to the homecoming game this year is between 65.2% and 86.6%.
99% of all possible intervals calculated this way will capture the true proportion of people who went to the homecoming game this year
Find the critical value, z*, for 91% confidence.
1.70
1.34
0.18
-1.34
Find the critical value, z* for 97%
1.88
2.17
-1.88
-2.17
Which confidence would result in a wider interval (assuming nothing else changed), 91% or 97%?
97%, z* is larger for higher confidence intervals
97%, the standard error is larger for higher confidence intervals
91%, z* is larger for lower confidence intervals
91%, the standard error is smaller for lower confidence intervals
If we fail to reject the Ho we could potentially be making what type of error?
type 1
type 2
you can't make an error if you fail to reject
The Ho is true
