8.25 The average life of a bread-making machine is 7years, with a standard deviation of 1 year. Assumingthat the lives of these machines follow approximatelya normal distribution, find(a) the probability that the mean life of a random sam-ple of 9 such machines falls between 6.4 and 7.2years;(b) the value of x to the right of which 15% of themeans computed from random samples of size 9would fall.

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Answered: 8.25 The average life of a bread-making…

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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An oceanographer claims that the mean dive duration of a North Atlantic right whale is 11.7 minutes. A random sample of 36 dive durations has a mean of 12.3 minutes and a standard deviation of 2.1 minutes. At a = 0.01 is there enough evidence to reject the oceanographer's claim? Complete parts (a) through (d) below. Assume the population is normally distributed. (a) Identify the claim and state H, and H, Ho Ha (Type integers or decimals. Do not round.) The claim is the hypothesis.
If the random variable of X is normally distributed with a mean of 50 and a standard deviation of 10, approximately what % of all possible observed values of X will lie between 30 and 70.
In the year 2033, Sarai Patterson is a leading traveling nurse. Sarai 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. Sarai 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. a) What is the setup for your null and alternative hypothesis? b) What is the value of the test statistic? c) What is/are the critical value(s)?
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.
The average life of a bread making machine is 7 years, with a standard deviation of 1 year. Assuming that the lives of these machines follow approximately a normal distribution, find a. the probability that the mean life of a random sample of 9 such machines falls between 6.4 and 7.2 years b. The value of to the right of which 15% of the means computed from random samples size 9 would fall. Round off to 5 decimal places
A population X is normally distributed with mean 71.5 and standard deviation 8.6. For each of the following values of x, find the corresponding z-number. Round off your answers to two decimal places. (a) x = 90(b) x = 80(c) x = 75(d) x = 70(e) x = 60(f) x = 50
3.2/2
The incubation time for a breed of chicks is normally distributed with a mean of 29 days and standard deviation of approximately 3 days. Look at the figure below and answer the following questions. If 1000 eggs are being incubated, how many chicks do we expect will hatch in the following time periods? (Note: In this problem, let us agree to think of a single day or a succession of days as a continuous interval of time. Assume all eggs eventually hatch.) (a) in 23 to 35 days chicks(b) in 26 to 32 days chicks(c) in 29 days or fewer chicks(d) in 20 to 38 days chicks
If the z-value for a given x of a random variable Z is z =1.06, and the distribution of X is normal with a mean of 60 and a standard deviation of 6, to what x-value does this z-value correspond?
A population of size 20 is sampled without replacement. The standard deviation of the population is 0.35. We require the standard error of the mean to be no more than 0.15. What is the minimum sample size?
A population has a mean of 300 and a standard deviation of 40. Suppose a simple random sample of size 100 is selected and x¯ is used to estimate μ .What is the probability that the sample mean will be within +/- 5 of the population mean?
A person's blood glucose level and diabetes are closely related. Let x be a random variable measured in milligrams of glucose per deciliter (1/10 of a liter) of blood. Suppose that after a 12-hour fast, the random variable x will have a distribution that is approximately normal with mean μ = 88 and standard deviation σ = 21. Note: After 50 years of age, both the mean and standard deviation tend to increase. For an adult (under 50) after a 12-hour fast, find the following probabilities. (Round your answers to four decimal places.) (a) x is more than 60(b) x is less than 110(c) x is between 60 and 110(d) x is greater than 140 (borderline diabetes starts at 140)

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