Camila is curious about the average length of the female blue whales her organization monitors. She takes a random sample of 4 female blue whales from this population. Their average recorded length is = 78 m and their standard deviation is s, = 10 m. The distribution of lengths in the sample is roughly symmetric with no obvious outliers. Based on this sample, which of the following is a 95% confidence interval for the mean length (in meters) of female blue whales?

Mason earned a score of 226 on Exam A that had a mean of 250 and a standard deviation of 40. He is about to take Exam B that has a mean of 550 and a standard deviation of 25. How well must Mason score on Exam B in order to do equivalently well as he did on Exam A? Assume that scores on each exam are normally distributed.

How can we also find normality?

Please help me with this question.

Loretta, who turns 91 this year, has heard that the mean systolic blood pressure among the elderly is 120 millimeters of mercury (mm Hg), but she believes that the actual value is higher. She bases her belief on a recently reported study of 19 randomly selected, elderly adults. The sample mean systolic blood pressure of the adults in the study was 121 mm Hg , and the sample standard deviation was 20 mm Hg. Assume that the population of systolic blood pressures of elderly adults is normally distributed. Based on the study, at the 0.1 level of significance, can it be concluded that μ , the mean systolic blood pressure among elderly adults, is greater than 120 mm Hg? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specified in the table. (a) State the null hypothesis H0? and the alternative hypothesis H1? . H0:? H1:? (b) Determine the type of test statistic to…

The president of a large university wishes to compare the standard deviation of the ages of students presently enrolled to previous years. The distribution of ages has been approximately normal. Find the 90% confidence interval for the population standard deviation of the student ages of the University. A random sample of 20 university students has a standard deviation of 6.1 years in a mean of 23.8 years what is the confidence interval of the population standard deviation?

Researchers want to compare the relative effectiveness of two popular diets. They randomly assign each of 400 volunteers to one of two Groups: A & B.  There are 200 volunteers in each group. Group A spends 6 months on Diet A. Group B spends 6 months on Diet B.   At the beginning of the study, the difference in average weight between the two groups was negligible. After the study, the Group A had lost on average 7.8 pounds with a standard deviation of 13.4 pounds, while the Group B had lost on average 5.3 pounds with a standard deviation of 14.8 pounds. Determine the z-score/test statistic for a two-tailed test with significance level α = 0.05 , accurate to 2 decimal places.

It seems these days that college graduates who are employed full time work more than 40 hour weeks. Data are available that can help us decide if this is true. A survey was recently sent to a group of adults selected at random. There were 22 respondents who were college graduates employed full time. The mean number of hours worked per week by these 22 respondents was 43 hours, with a standard deviation of 8 hours.  Assume that the population of hours worked per week by college graduates employed full time is normally distributed with mean. Can we conclude that mean is greater than 40 hours? Use the 0.1 level of significance. Perform a one tailed test, and complete the parts below.

A survey of 30 adults found that the mean age of a person's vehicle is 3.6 years. Assuming the population distribution is normal and the standard deviation is 2 years, find the 94% confidence interval for the population mean. What is the meaning of this confidence interval?

Pyramid Lake is on the Paiute Indian Reservation in Nevada. The lake is famous for cutthroat trout. Suppose a friend tells you that the average length of trout caught in Pyramid Lake isμ=19 inches. However, a survey reported that of a simple random sample of 38 fish caught, the mean length was 19.9 inches, with estimated standard deviation of 3.1 inches. Do these data indicate that the average length of a trout caught in Pyramid Lake is different from μ=19inches? Use α=0.001. What is the value of the test statistic? (Round your answer to two decimal places.)Find the P-value. (Round your answer to four decimal places.)