You are a researcher studying the lifespan of a certain species of bacteria.  A preliminary sample of 35 bacteria reveals a sample mean of ¯x=76x¯=76 hours. The population standard deviation is known to be 5.6  hours.  You would like to estimate the mean lifespan for this species of bacteria to within a margin of error of 0.4 hours at a 90% level of confidence. How many more

A population of scores has µ=44. In this population, a score of X= 40 corresponds to z= - 0. 50. What is the population standard deviation?

A sample of size 50 will be drawn from a population with mean 76 and standard deviation 14. Find the 69th percentile of  x.

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 7.97.9 parts/million (ppm). A researcher believes that the current ozone level is at an excess level. The mean of 2424 samples is 8.18.1 ppm with a variance of 0.250.25. Does the data support the claim at the 0.10.1 level? Assume the population distribution is approximately normal. Step 3 of 5:  Specify if the test is one-tailed or two-tailed.

The life of a butterfly is normally distributed with a mean of 50 days. You took a random sample of 25 such butterflies. The mean life for this sample is 47 days a standard deviation of 3 days. At α = 0.05. a. Test to see if the average life of a butterfly is different from 50 days. b. Your friend believes that the life of a butterfly is less than 50 days. Is she correct?

Pyramid Lake is on the Palute Indian Reservation in Nevada. The lake is famous for cutthroat trout. Suppose a tells you that the average length of trout caught in Pyramid Lake Is mu = 19 Inches. Howevera survey reported that of a random sample of 46 fish caught, the mean length was overline x =18.6 lnch , with estimated standard s = 2.7 inches. these data Indicate that the average length of a trout caught in Pyramid Lake less than mu = 19 inches? Use a=0.05 Please answer ONLY parts D & E

A queueing system has an arrival rate of 37 visitors per day (standard deviation of 32) and a service rate of 42 visitors per day (standard deviation of 25). (Round your answer to three decimal places.) What is the coefficient of variation of the arrival rate?

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 7.9 parts/million (ppm). A researcher believes that the current ozone level is at an excess level. The mean of 24 samples is 8.1 ppm with a variance of 0.25. Does the data support the claim at the 0.1 level? Assume the population distribution is approximately normal. Step 5 of 5:  Make the decision to reject or fail to reject the null hypothesis.

Solve question 9, Part A, Part B and Part C only.

A manufacturer knows that their items have a normally distributed lifespan, with a mean of 10.3 years, and standard deviation of 0.5 years. The 6% of items with the shortest lifespan will last less than how many years? Give your answer to one decimal place.