7. (简答题, 6.0分)Suppose that 75% of people in a certain metropolitan area live in the city and 25% of the people live in the suburbs. If1200 people attending a certain concert represent a random sample from the metropolitan area, what is the probabilty(2)=0.9772 (1) = 0.8413that the number of people from the suburbs attending the conert will be fewer than 270?(*(3)=0.9987 (3.33) = 0.9996beta段落格式 • 字体字号 B I U A, Ξ Ξ Ξ Ω ππP23

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Answered: 7. (简答题 6.0分) Suppose that 75% of…

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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Suppose that average male weight in the US is 175 pounds with a standard deviation of 25 pounds. Suppose you randomly select 1,000 male Americans and ask their weight, and average the 1,000 numbers to compute a sample mean X. a) What does the law of large numbers tell you about X, the average of the 1,000? Be precise in your answer using about 1 to 3 sentences.
In a random sample of n = 200 adults, 94 individuals say that they believe in love at first sight. (a) Calculate the value of = sample proportion that believes in love at first sight. (b) Calculate the standard error, s.e. of . (Round your answer to three decimal places.)
Suppose that there are 4 deaths due to stomach can- cer among workers in a tire plant from 1/1/64 to 12/31/83, while 2.5 are expected based on U.S. mortality rates. Provide a 95% CI for the expected number of deaths from stomach cancer over 20 years among the tire workers. Is the number of cases of stomach cancer excessive?
4. In a population of 10,000 businesses, we want to estimate the average sales Y For that, we sample n = = 100 businesses using simple random sampling. Furthermore, we have at our disposal the auxiliary information 'number of employees', denoted by x, for each business. The data coming from the sample are: - - X = 50 employees (true mean for x ), - Ŷ = 5.2 × 10 Euros (average sales in the sample), - X = 45 employees (sample mean), - s² = 25 x 1010 (sample variance of y₁), - 2 - s² = 15 (sample variance of x^), x p=0.80 (sample linear correlation coefficient between x and y ), a. Calculate the ratio estimate of Ỹ. Is this estimate unbiased or biased? Explain. b. What is the ‘true' variance formula for this estimate? c. Calculate an estimate of the true variance. Is the variance estimate unbiased or biased? Explain. d. Give a 95% confidence interval for Y.
A research study was conducted about gender differences in 'sexting'. The researcher believed that the proportion of girls involved in 'sexting' is different from the proportion of boys involved. The data collected in the spring of among a random sample of middle and high school students in a large school district in is summarized next: out of 380 females 43 sent 'sexts' and out of 410 males 64 sent 'sexts'. Is the proportion of girls sending sexts different from the proportion of boys 'sexting'? Choose the appropriate procedure. Procedure: Assumptions: (select everything that applies) Population standard deviations are known Normal populations Sample sizes are both greater than 30 Population standard deviation are unknown but assumed equal Paired samples Population standard deviation are unknown Simple random samples The number of positive and negative responses are both greater than 10 for both samples Independent samples
21a)
In a random sample of n = 600 drivers, 168 individuals say that they never wear a seatbelt when driving. (a) Give a numerical value of p̂ = sample proportion that never wears a seatbelt when driving. p̂ = (b) Calculate the standard error, s.e., of p̂. (Give the answer to four decimal places.) s.e.(p̂) = (c) In a different survey of n = 1200 drivers, 336 people say they never wear a seatbelt when driving. Give numerical values for p̂ and the standard error, s.e., of p̂. (Give the answer to four decimal places.) p̂ = s.e.(p̂)=

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