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Statistics Questions for Research Methodology Course
Deadline: 4pm Wednesday 5th December 2018
Submission: Electronic submission. If you wish to do the questions by hand (recommended), then please scan the work and submit it as a pdf or word document.
1.A prospective purchaser of resistors buys a sample of size from the manufacturer to check that their average value does not vary by more than 3% from the average quoted value of all resistors from the same manufacturer, with a probability of 0.05. If the values of the resistors are normally distributed with a standard deviation that is 15% of the value , how many would have to be bought (i.e. estimate ) (10 marks)

2.The resistivity of a material is the standardized measure of resistance. It is calculated from the resistance of a sample using the following equation:

Where the cross-sectional area and is the distance between voltage electrodes. It assumes that the sample is bar-shaped. (10 marks)

The resistance of four samples of titanium metal was independently measured including their dimensions. Calculate the weighted average resistivity and its error using the data below.
Sample number ( (cm) (cm) (cm) (cm) (cm) (cm)
1 230.2 2.0 0.1 0.1 0.1 1.5 0.2
2 163.4 4.0 0.1 0.3 0.1 4.0 0.5
3 15.4 5.0 0.1 1.2 0.1 2.4 0.2
4 114.2 1.0 0.1 2.4 0.1 8.2 0.3

3.A group of 9 students entering the materials science department at UCL has a mean score of 78% in national examinations, with a standard deviation on the mean of 17%. The national average for the examinations is 65%. What is the probability that the materials science department is getting better than average students? (10 marks)
n 1 2 3 4 5 6 7
A 71 75 79 71 70 73 72
B 70 68 72 73 67 - -
4.The examination marks of two groups of students are shown in the table below. Group A attended a revision lecture before the examination but group B did not.

Did attending the revision lecture make an improvement on the average student mark at the 2% level?
Construct a null hypothesis and test it using a Student’s t- test. (10 marks)

Methodology留学生讲解、辅导CS/python编程语言、讲解C/C++设计 辅导R语言程序|辅导Web开发

Methodology留学生讲解、辅导CS/python编程语言、讲解C/C++设计辅导R语言程序|辅导Web开发