The average life of a bread-making machine is 8 years, with a standard deviation of 2. Assuming that the lives of these machines follow approximately a normal distribution, find • The probability that the mean life of a random sample of 11 such machines falls between 7.2 and 8.4 years. • The value of k to the right of which 20% of the means computed from random samples of size 11 would fall.

The average life of a bread-making machine is 8 years, with a standard deviation of 2. Assuming that the lives of these machines follow approximately a normal distribution, find • The probability that the mean life of a random sample of 11 such machines falls between 7.2 and 8.4 years. • The value of k to the right of which 20% of the means computed from random samples of size 11 would fall.

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

In a random sample of 29 residents living in major cities on the West Coast (Group 1) and 29 residents living in major cities on the East Coast (Group 2), each individual was asked their age. The results can be seen in the table below. The population standard deviation of the age in West Coast cities is known to be 11.2 years and in East Coast cities is known to be 9.3 years. Assume the populations are normally distributed. Run a test at a 0.05 level of significance to test if west coast cities are, on average, older. West Coast (Group 1) East Coast (Group 2) 25 34 47 45 18 37 38 20 30 19 50 26 52 79 61 46 40 29 22 55 34 23 35 35 55 36 60 51 68 41 20 50 33 32 36 38 37 26 42 44 60 19 71 28 54 27 20 18 45 30 52 20 34 22 57 43 64 62 Enter the P-Value - round to 4 decimal places. Make sure you put…
A company manufactures light bulbs. The company wants the bulbs to have a mean life span of 1010 hours. This average is maintained by periodically testing random samples of 16 light bulbs. If the t-value falls between - to 9g and to go- then the company will be satisfied that it is manufacturing acceptable light bulbs. For a random sample, the mean life span of the sample is 1015 hours and the standard deviation is 26 hours. Assume that life spans are approximately normally distributed. Is the company making acceptable light bulbs? Explain. The company V making acceptable light bulbs because the t-value for the sample is t= and to on =. (Round to two decimal places as needed.)
A person's level of blood glucose and diabetes are closely related. Let x be a random variablemeasured in milligrams of glucose per deciliter (1/10 of a liter) of blood. Suppose that after a12-hour fast, the random variable x will have a distribution that is approximately normal withmean μ = 84 and standard deviation of σ = 26 What is the probability that, for an adult after a12-hour fast, x is less than 81? Group of answer choices 0.546 0.454 0.023 0.273 0.227
The ages of a group of 149 randomly selected adult females have a standard deviation of 16.5 years. Assume that the ages of female statistics students have less variation than ages of females in the general population, so let σ=16.5 years for the sample size calculation. How many female statistics student ages must be obtained in order to estimate the mean age of all female statisticsstudents? Assume that we want 90% confidence that the sample mean is within one-half year of the population mean. Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general population? Question content area bottom Part 1 The required sample size is enter your response here.
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.
The distribution of heights of a certain breed of terrier dogs has a mean height of 70 cm and standard deviation of 8 cm, whereas the distribution of heights of a certain breed of poodles has a mean height of 30 cm with a standard deviation of 5 cm. Assuming that the sample means can be measured to any degree of accuracy, find the probability that the sample mean for a random sample of heights of 60 terriers exceeds the sample mean for a random sample of 80 poodles by at most 44 cm.
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
The ages of a group of 156 randomly selected adult females have a standard deviation of 17.4 years. Assume that the ages of female statistics students have less variation than ages of females in the general population, so let σ=17.4 years for the sample size calculation. How many female statistics student ages must be obtained in order to estimate the mean age of all female statistics students? Assume that we want 98% confidence that the sample mean is within one-half year of the population mean. Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general population?
If a population forms a normal shaped distribution with µ =40 and σ = 8 and a sample of 16 scores from this population has a mean of 36, would this sample be relatively typical or extreme?
1. The strength of steel wire made by an existing process is normally distributed with a mean of 1550 and a standard deviation of 170. A batch of wire is made by a new process, and a random sample consisting of 25 measurements gives an average strength of 1316. Assume that the standard deviation does not change. Is there evidence at the 1% level of significance that the new process gives a larger mean strength than the old? To answer this question, the null hypothesis could be stated as A. μ= 1550 psi B. μ> 1550 psi C.µ + 1550 psi D. μ< 1550 psi
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 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?