Allen's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther.† Suppose a small group of 11 Allen's hummingbirds has been under study in Arizona. The average weight for these birds is x = 3.15 grams. Based on previous studies, we can assume that the weights of Allen's hummingbirds have a
A-Find the
=__ hummingbirds
Do you want to own your own candy store? Wow! With some interest in running your own business and a decent credit rating, you can probably get a bank loan on startup costs for franchises such as Candy Express, The Fudge Company, Karmel Corn, and Rocky Mountain Chocolate Factory. Startup costs (in thousands of dollars) for a random sample of candy stores are given below. Assume that the population of x values has an approximately normal distribution.
93 | 171 | 133 | 99 | 75 | 94 | 116 | 100 | 85 |
B-Find a 90% confidence interval for the population average startup costs ? for candy store franchises. (Round your answers to one decimal place.)
lower limit | =__ thousand dollars |
upper limit | =__thousand dollars |
For this problem, carry at least four digits after the decimal in your calculations. Answers may vary slightly due to rounding.
In a random sample of 63 professional actors, it was found that 43 were extroverts.
C-(b) Find a 95% confidence interval for p. (Round your answers to two decimal places.)
lower limit | =__ |
upper limit | =__ |
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- A group of students sampled water from 34 lakes in St. Joseph County. If the mean dissolvedoxygen level was 3.2 with a standard deviation of .57 find a 90% confidence interval for thedissolved oxygen levels in St Joseph County lakes.arrow_forward1. The strength of a fiber is normally distributed with a known population standard deviation of 12 kg. An engineer sampled random pieces of fiber, and got the following data: 43, 54, 74.2, 47, 61.6, 80, 38, 40, 32 Find the 96% confidence interval for the mean strength of the fiber.arrow_forwardFollowing an oil spill, a particular region of the ocean is being tested for the level of a chemical called naphthalene. It is considered fact that fish from the region will be safe to eat if, and only if, the mean naphthalene level in the region is less than 3.3 parts per billion. A set of water specimens will be randomly selected from the region and tested, and if the results provide convinving evidence that the mean naphthalene level is less than 3.3, then the sale of fish from the region will be made legal. Which of the following describes a Type I error and its consequences? A) the authorities fail to obtain convincing evidence that the mean naphthalene level is less than 3.3, and do not legalize the sale of fish from the region when in fact the fish are SAFE for consumption. B) The definition of a Type I error depends on the actual results of the study in question C) The authorities fail to obtain convincing evidence that the mean naphthalene level is less than 3.3, and do not…arrow_forward
- At the local fish hatchery we take a random sample of 21 trout from one of the holding pens. The trout in the sample have a mean length of 11.2 inches with a standard deviation of .73 inches. Construct and interpret a 95% confidence interval for the mean length of all trout in this holding pen. Type your interpretation sentence in the written response box.arrow_forwardFind the critical value tc for a 95% confidence level when the sample size is 18. Use Table 4 on page A10 (Appendix) A. 1.740 B. 2.110 C. 2.101 D. 1.734arrow_forwardBrads's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther.† Suppose a small group of 15 Brad's hummingbirds has been under study in Arizona. The average weight for these birds is x = 3.15 grams. Based on previous studies, we can assume that the weights of Brads's hummingbirds have a normal distribution, with ? = 0.22 gram. a) Find the sample size necessary for an 80% confidence level with a maximal margin of error E = 0.12 for the mean weights of the hummingbirds. (Round up to the nearest whole number.) b) Find an 80% confidence interval for the average weights of Allen's hummingbirds in the study region. What is the margin of error? (Round your answers to two decimal places.)lower limit =upper limit =margin of error =arrow_forward
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