Electric Light tested a sample of 20 lightbulbs which produced a mean lifetime of 114 hours...
Electric Light tested a sample of 20 lightbulbs which produced a mean lifetime of 114 hours with a standard deviation of 4.7 hours. Construct 98% confidence interval for the true mean lifetime of the lightbulbs.
Homework Answers
Answer:
Given,
Sample n = 20
Mean = 114
Standard deviation = 4.7
alpha = 1 - 0.98 = 0.02
alpha2 = 0.01
degree of freedom = n - 1
= 20 - 1
= 19
t(alpha/2,df) = t(0.01 , 19) = 2.54
Interval = xbar +/- t*s/sqrt(n)
substitute values
= 114 +/- 2.54*4.7/sqrt(20)
= 114 +/- 2.67
= (114 - 2.67 , 114 + 2.67)
= (111.33 , 116.67)
Interval = (111.33 , 116.67)
Add Answer to:
Electric Light tested a sample of 20 lightbulbs which produced a
mean lifetime of 114 hours...
A sample of size n=50 is taken from the production of lightbulbs at a certain factory....
A sample of size n=50 is taken from the production of lightbulbs at a certain factory. The sample mean of the lifetime of these 50 lightbulbs is found to be to X=1570 hours. Assume that the population standard deviation is a = 120 hours. (a) Construct a 95% confidence interval for . (b) What sample size is needed so that the length of the interval is 30 hours with 95% confidence?
The lifetime of a certain brand of electric light bulb is known to have a standard...
The lifetime of a certain brand of electric light bulb is known to have a standard deviation of 47 hours. Suppose that a random sample of 150 bulbs of this brand has a mean lifetime of 478 hours. Find a 90% confidence interval for the true mean lifetime of all light bulbs of this brand. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. What is the...
The lifetime of a certain brand of electric light bulb is known to have a standard...
The lifetime of a certain brand of electric light bulb is known to have a standard deviation of 49 hours. Suppose that a random sample of 90 bulbs of this brand has a mean lifetime of 500 hours. Find a 90% confidence interval for the true mean lifetime of all light bulbs of this brand. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. What is the...
The quality control manager at a light bulb factory needs to estimate the mean life of...
The quality control manager at a light bulb factory needs to estimate the mean life of a large shipment of light bulbs. The standard deviation is 98 hours. A random sample of 49 light bulbs indicated a sample mean life of 300 hours. (a) Construct a 99% confidence interval estimate for the population mean life of light bulbs in this shipment. The 99% confidence interval estimate is from a lower limit of 263.9 hours to an upper limit of 336.1...
Lifetime of electronics: In a simple random sample of 100 electronic components produced by a certain...
Lifetime of electronics: In a simple random sample of 100 electronic components produced by a certain method, the mean lifetime was 125 hours. Assume that component lifetimes are normally distributed with population standard deviation - 20 hours. Round the critical value to no less than three decimal places. Part: 0/2 Part 1 of 2 (a) Construct a 90% confidence interval for the mean battery life. Round the answer to the nearest whole number. A 90% confidence interval for the mean...
1. An electric firm manufactures light bulbs that have a lifetime, X, that is approximately norma...
1. An electric firm manufactures light bulbs that have a lifetime, X, that is approximately normally distributed with a standard deviation of 100 hours. Prior experience leads the firm to establish that the mean of X (or mean lifetime), say , follows a normal distribution with mean 140-800 hours and standard deviation σ0 10 hours. If a random sample of 25 bulbs examined turns out an average lifetime of 780 hours, solve the following. (a) Find a 95% Bayesian estinate...
Lightbulbs of a certain type are advertised as having an average lifetime of 750 hours. The...
Lightbulbs of a certain type are advertised as having an average lifetime of 750 hours. The price of these bulbs is very favorable, so a potential customer has decided to go ahead with a purchase arrangement unless it can be conclusively demonstrated that the true average lifetime is smaller than what is advertised. A random sample of 50 bulbs was selected, and the sample mean was found to be 738.44 with a standard deviation of 38.20 and a standard error...
Lightbulbs of a certain type are advertised as having an average lifetime of 750 hours. The...
Lightbulbs of a certain type are advertised as having an average lifetime of 750 hours. The price of these bulbs is very favorable, so a potential customer has decided to go ahead with a purchase arrangement unless it can be conclusively demonstrated that the true average lifetime is smaller than what is advertised. A random sample of 50 bulbs was selected, and the sample mean was found to be 738.44 with a standard deviation of 38.20 and a standard error...
Westinghouse wants to determine the lifetime of its standard lightbulbs with an error 13 hours. Standard...
Westinghouse wants to determine the lifetime of its standard lightbulbs with an error 13 hours. Standard deviation is 120 hours. What sample size should they have to be 95% confident of the lifetime of their standard lightbulb? a) 18.09 lightbulbs b) 19 lightbulbs c) 328 lightbulbs d) 327.33 lightbulbs
Light bulbs with a stated mean lifetime of 750 hours have been stored in a warehouse...
Light bulbs with a stated mean lifetime of 750 hours have been stored in a warehouse for years . A sample of 10 of these bulbs is selected at random and destructively tested . The results of this sample gave a mean of 720 hours with a standard deviation of 40 hours . You wish to test whether prolong storage has significantly reduced the life expectancy of these light bulbs . You can assume that bulb lifetime is normally distributed....
A sample of size n=50 is taken from the production of lightbulbs at a certain factory. The sample mean of the lifetime of these 50 lightbulbs is found to be to X=1570 hours. Assume that the population standard deviation is a = 120 hours. (a) Construct a 95% confidence interval for . (b) What sample size is needed so that the length of the interval is 30 hours with 95% confidence?
The lifetime of a certain brand of electric light bulb is known to have a standard deviation of 47 hours. Suppose that a random sample of 150 bulbs of this brand has a mean lifetime of 478 hours. Find a 90% confidence interval for the true mean lifetime of all light bulbs of this brand. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. What is the...
The lifetime of a certain brand of electric light bulb is known to have a standard deviation of 49 hours. Suppose that a random sample of 90 bulbs of this brand has a mean lifetime of 500 hours. Find a 90% confidence interval for the true mean lifetime of all light bulbs of this brand. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. What is the...
Lifetime of electronics: In a simple random sample of 100 electronic components produced by a certain method, the mean lifetime was 125 hours. Assume that component lifetimes are normally distributed with population standard deviation - 20 hours. Round the critical value to no less than three decimal places. Part: 0/2 Part 1 of 2 (a) Construct a 90% confidence interval for the mean battery life. Round the answer to the nearest whole number. A 90% confidence interval for the mean...
1. An electric firm manufactures light bulbs that have a lifetime, X, that is approximately normally distributed with a standard deviation of 100 hours. Prior experience leads the firm to establish that the mean of X (or mean lifetime), say , follows a normal distribution with mean 140-800 hours and standard deviation σ0 10 hours. If a random sample of 25 bulbs examined turns out an average lifetime of 780 hours, solve the following. (a) Find a 95% Bayesian estinate...
Most questions answered within 3 hours.
-
Where is the error in this code sequence?
String s1 = "Hello";
String s2 = "ello";...
asked 10 months ago -
Financial data for Joel de Paris, Inc., for last year
follow:
Joel de Paris, Inc.
Balance...
asked 10 months ago -
Consider this reaction:
Al2(SO4)3 (aq)+ BaCl3
(aq) Al2Cl6 (aq)- +
3BaSO4(s) . What is the...
asked 10 months ago -
Suppose that Savneet is considering increasing her
recent random sample from 20 car rentals to 40...
asked 10 months ago -
Trucks arrive at an unloading terminal at an average rate of 120
per hour.
Trucks arrive...
asked 10 months ago -
Why are methanol and ethanol completely soluble in water while
octanol is not very little soluble....
asked 10 months ago -
A facilities manager at a university reads in a research report
that the mean amount of...
asked 10 months ago -
When the CuSO4 is rehydrated by adding water to the anhydrous
compound, is this an endothermic...
asked 10 months ago -
A ray of sunlight is passing from diamond into crown glass; the
angle of incidence is...
asked 10 months ago -
A block of mass 0.249 kg is placed on top of a light, vertical
spring of...
asked 10 months ago -
how do the kidneys compensate in the presences of acidosis
a) trigger hyperventilate
b) reserve acid...
asked 10 months ago -
Question 501 pts
The rental rate of capital to the firm increases. Which of the
following...
asked 10 months ago