Statistics Word Problems? - what type of engineers would be involved in cars
A company wants to estimate the average annual real income of the customer. It randomly samples 200 of its customers. The average annual income of $ 55,200 was a standard deviation of $ 1,500. Find a confidence interval 95% to the average real income of the annual "the company's customers.
A company wants to estimate the average annual real income of the customer. The company must be at least $ 200 for half the truth. The Company believes that the true population standard deviation is about $ 1300th If the 95% confidence of finding the sample size necessary to achieve the desired accuracy.
An engineer in the automobile safety is an estimate of the average cost to repair a Chevy Corvette involved in a collision 30 mph, the engineer of 18 accidents Corvettes and find the damage to $ 17,500 with a standard deviation of $ 2400th Find a confidence interval of 95% with the actual average cost for such a car repair.
A listener wants, what percentage of cases of bank loan estimate is incomplete. The listener wants to be wimeager 7% of the true proportion when using a 95%. How many files it is necessary that the auditor of the test? There are no estimates on the share is available, then use 0.5 for the proportion of the population.
Saturday, February 6, 2010
What Type Of Engineers Would Be Involved In Cars Statistics Word Problems?
2 comments:
Some explanations
zz * implies that star
x denotes the time (various)
No means that the sample size
A company wants to estimate the average annual real income of the customer. It randomly samples 200 of its customers. The average annual income of $ 55,200 was a standard deviation of $ 1,500. Find a confidence interval 95% to the average real income of the annual "the company's customers.
n = 200
Example:
Average = 55,200
SD = 1.500
Using z *
Deviation 1500/sqrt (200) = 106,066
z * 95% confidence level = 1.96
55,200 + / - or 1.96x106.066
55,200 + / - 207.89
Answer: 54,992.11 to 55,407.89
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A company wants to estimate the average annual real income of the customer. The company must be at least $ 200 for half the truth. The Company believes that the true population standard deviation is about $ 1300th If the 95% confidence of finding the sample size necessary to achieve the desired accuracy.
Population:
Standard deviation = 1300
Example:
Error = 200
weez *
z * 95% confidence level = 1.96
= (N 1.96x1300/200) ^ 2
n = 162.31, always rounded to the nearest 163 or
Answer: At least 163 people in the sample
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An engineer in the automobile safety is an estimate of the average cost to repair a Chevy Corvette involved in a collision 30 mph, the engineer of 18 accidents Corvettes and find the damage to $ 17,500 with a standard deviation of $ 2400th Find a confidence interval of 95% with the actual average cost for such a car repair.
Example:
n = 18
Average = 17,500
Standard deviation = 2400
Using z *
z * 95% confidence level = 1.96
Deviation 2400/sqrt (18) = 565,685
17,500 + / - 1.96x565.685
17,500 + / - 1108.74
Answer: 16,391.26 to 18,608.74
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A listener wants, what percentage of cases of bank loan estimate is incomplete. The listener is within 7% of the true proportion is using a 95%. How many files it is necessary that the auditor of the test? N eStimate share is available, then use 0.5 for the proportion of the population.
Example:
Error rate of 7%, or 0.07
z * 95 confidence level 1.96%
Population:
p = 0.5
Distribution used to get to n
n = ((1.96/0.07) ^ 2) x 0.5 (1-0,5)
n = 784x0.5 (1-0,5)
n = 785x0.5x0.5
n = 196 of his person and should not meet as a whole.
Answer: at least 196 cases.
Some additional remarks
The idea is to use z * t * times when you know the standard deviation of the population, always use Z *. It seems that the same type of question to question 1 3 question.
In question 4, it is necessary, the distribution of shares to be used by equations similar, with minor modifications.
* Still confused? rewrite
The first number is not enough information to answer the question addressed.
If it only 200 customers, the average is exactly what it is.
If the customer is then 2 trillion size of the sample is too small to provide reliable statistics. Of course there are many people around the world. I have used this figure to the point. The limits of the confidence level does not depend on the size of the population.
This type of error is each year in trying a sample of potential voters will approve on.
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