BIG Corporation advertises that its light bulbs have a mean lifetime, μ, of 2800 hours. Suppose we have good reason to believe that μ is different from 2800 hours and decide to do a statistical test of the claim. We choose a random sample of light bulbs manufactured by BIG and find that the mean lifetime for this sample is 2620 hours and that the sample standard deviation of the lifetimes is 650 hours. Based on this information, complete the parts below. (a) What are the null hypothesis H0 and the alternative hypothesis H1 that should be used for the test? H0: H1: (b) Suppose that we decide not to reject the null hypothesis. What sort of error might we be making?   ▼(Choose one)   (c) Suppose the true mean lifetime of BIG's light bulbs is  2600 hours. Fill in the blanks to describe a Type II error. A Type II error would be ▼(Choose one) the hypothesis that  μ is ▼(Choose one) ▼(Choose one) when, in fact, μ is ▼(Choose one) .

A population has a mean μ = 73 and a standard deviation o = 28. Find the mean and standard deviation of a sampling distribution of sample means with sample size n = 257. Hx ox (Simplify your answer.) (Type an integer or decimal rounded to three decimal places as needed.)

In the year 2033, katy perry is a leading traveling nurse. Katy is interested in reducing the mean recovery time for patients after experiencing a serious injury (assume recovery times are normally distributed). Suppose the mean recovery time is presently 8.6 months. Katy takes a random sample of 46 patients that have experienced serious injury to participate in a new treatment program and finds the sample mean is 8.1 months and a sample standard deviation of 1.2 months. Using α = 0.05, answer the following questions. g) What is the interpretation (not your conclusions) of the p value in the context of the problem you found in part e? h) What are your conclusions in the context of the problem? Relate your conclusions to the test statistic and critical value, confidence interval and p value.

3.2/2

There are many situations in which we want to compare means from populations having standard deviations that are equal. This method applies even if the standard deviations are known to be only approximately equal. Consider a report regarding average incidence of fox rabies in two regions. For region I, n1 = 16, x1 ≈ 4.73, and s1 = 2.84 and for region II, n2 = 15, x2 ≈ 3.93, and s2 = 2.45. The two sample standard deviations are sufficiently close that we can assume ?1 = ?2. Use the method of pooled standard deviation to consider the report, testing if there is a difference in population mean average incidence of rabies at the 5% level of significance. (Round your answer to three decimal places.) t =

Deanna is the principal at a Midwestern middle school and wants to know the average IQ of all female, seventh grade students.  She does not know anything about what the population distribution looks like.  She took a simple random sample of 31 seventh-grade girls in her school and found the average IQ score in her sample was 105.8 and the standard deviation was 15. Using the sample standard deviation above to estimate the population standard deviation, what is the minimum sample size needed for a 99.5% confidence interval to have a margin of error of no more than 2.3?

A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1458 and the standard deviation was 312. The test scores of four students selected at random are 1860, 1220, 2150, and 1340. Find the z-scores that correspond to each value and determine whether any of the values are unusual. The z-score for 1860 is (Round to two decimal plaes as needed.)

The salaries of professional baseball players are heavily skewed right with a mean of $3.2 million and a standard deviation of $2 million. The salaries of professional football players are also heavily skewed right with a mean of $1.9 million and a standard deviation of $1.5 million. A random sample of 40 baseball players’ salaries and 35 football players’ salaries is selected. The mean salary is determined for both samples. Let  represent the difference in the mean salaries for baseball and football players. Which of the following represents the shape of the sampling distribution for ? skewed right since the populations are both right skewed skewed right since the differences in salaries cannot be negative approximately Normal since both sample sizes are greater than 30 approximately Normal since the sum of the sample sizes is greater than 30

The lengths of pregnancies in a small rural village are normally distributed with a mean of 267 days and a standard deviation of 15 days.In what range would you expect to find the middle 95% of most pregnancies?Between  and .If you were to draw samples of size 55 from this population, in what range would you expect to find the middle 95% of most averages for the lengths of pregnancies in the sample?Between  and .