PracticeTest-3-Fall17(1 ractice,Test-3-Fall 1 7%20(1)pdf [I point] The t-distrib

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PracticeTest-3-Fall17(1 ractice,Test-3-Fall 1 7%20(1)pdf [I point] The t-distribution should be used in place of the standard normal (z) distribution when the population standard deviation is unknown and sample size is less than 25 True False er, No. should be used in testing the difference of two independent [1 point] The population populations True False [1 point] The value of should be calculated when you have sample data with 58 observations and population standard deviation is unknown. True False II point] For a hypothesis testing problem where you wish to compare two population means, ni = n2 10 and population standard deviations unknown, the first test statistic used in the complete testing procedure will be (circle): Zo I2 points) Identify the standard normal equation that would be required to answer the following . Concrete-filled tube columns are used as structural support due to their excellent seismic resistant properties. A structural engineer conducted an experiment and recorded failure strengths of 12 samples. The standard deviation of measurements was nown that the failure strengths are-pormally distributed with mean 3,000 kN for this type of column. What is the likelihood of the mean fsilure strength of 12 samples being lower than 2,750 kN? A machining operation produces steel shafts having diameters that are normally distnbuted with a mean of 1.005 inches and a standard deviation of 0.010 inch. Specifications call for diameters to fall ithin the interval 1.00 ± 0.02 inches. What percentage of the output of this operation will fail to neet specifications?

Explanation / Answer

1) TRUE

REASON: Here the population standard deviation is unknown. It is one of the assumption of t test and also n<30

2) TRUE

REASON: muD = mu1-mu2

3) FALSE

REASON: Equality of variances tested by Levens 'F' test

4) t0 statistic

Reason: Population standard deviations are unkown and sample sizes <30

5) Z= (3000-2750)/(989/SQRT(12)) = 0.8757

6)

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