It is known from past information that the probability offailing to finish an Ironman (called a DNF) is 15%. Suppose we takea sample of 100 Ironman races over the past few years and find thatthe DNF percentage is 12%. We are interested in seeing if there hasbeen a significant decrease in the number of DNFs. Use alpha=0.05.Find the 95% confidence interval for the percentage of DNFs.
| a. | (0.0665, 0.1735) |
| b. | (0.0555, 0.1845) |
| c. | (0.1179, 0.1221) |
| d. | (0.0563, 0.1837) |
It is known from past information that the probability offailing to finish an Ironman (called a DNF) is 15%. Suppose we takea sample of 100 Ironman races over the past few years and find thatthe DNF percentage is 12%. We are interested in seeing if there hasbeen a significant decrease in the number of DNFs. Use alpha=0.05.The null and the alternative hypotheses are:
| a. | Null hypothesis: The population proportion is less than or equalto 0.12 Alternative hypothesis: The population proportion is greaterthan 0.12 |
| b. | Null hypothesis: The population proportion is less than or equalto 0.15 Alternative hypothesis: The population proportion is greaterthan 0.15 |
| c. | Null hypothesis: The population proportion is greater than orequal to 0.15 Alternative hypothesis: The population proportion is less than0.15 |
| d. | Null hypothesis: The sample proportion is less than or equal to0.15 Alternative hypothesis: The sample proportion is greater than0.15 |
It is known from past information that the probability offailing to finish an Ironman (called a DNF) is 15%. Suppose we takea sample of 100 Ironman races over the past few years and find thatthe DNF percentage is 12%. We are interested in seeing if there hasbeen a significant decrease in the number of DNFs. Use alpha=0.05.The test statistic is:
| a. | t= -0.84 |
| b. | t= -0.92 |
| c. | z= -0.84 |
| d. | z= -0.92 |
It is known from past information that the probability offailing to finish an Ironman (called a DNF) is 15%. Suppose we takea sample of 100 Ironman races over the past few years and find thatthe DNF percentage is 12%. We are interested in seeing if there hasbeen a significant decrease in the number of DNFs. Use alpha=0.05.The p-value is:
| a. | 0.1798 |
| b. | 0.2005 |
| c. | 0.7995 |
| d. | p-value greater than 0.20 |
It is known from past information that the probability offailing to finish an Ironman (called a DNF) is 15%. Suppose we takea sample of 100 Ironman races over the past few years and find thatthe DNF percentage is 12%. We are interested in seeing if there hasbeen a significant decrease in the number of DNFs. Use alpha=0.05.Assuming no prior estimate of p is available, what is the samplesize that would need to be taken if we wanted to have a margin oferror of 0.08 or less with 95% confidence?
