Read the following and answer the questions.  Traffic department wants to know if automobile accident is a very serious problem in Central compared to other districts in Hong Kong. Nine intersections in Central have been chosen at random. The number of accidents at those intersections has been recorded for three months. The average number of accidents at an intersection in Hong Kong in the past three months is 3.    The number of accidents at the chosen intersections in Central:  A  B  C  D  E  F  G  H  I  6  8  7  4  8  7  7  11  5  Calculate the mean number of accidents in Central.   Calculate the sample standard deviation for the number of accidents in Central.   State the null hypothesis if traffic department wants to test whether automobile accident is a very serious problem in Central compared to other districts in Hong Kong.   Continue from part c, state the corresponding alternative hypothesis of the test.   Continue from part c, calculate the test statistics of the test.   Continue from part e, what is the critical value of the test if the significant level is 5%?   According to the test, is automobile accident a very serious problem in Central compared to other districts in Hong Kong?       A team of experts claims that a modification in the type of light will reduce these accidents. The lights at the chosen intersections in Central were modified. The number of accidents before and after the modification has been recorded.     A  B  C  D  E  F  G  H  I  Before  6  8  7  4  8  7  7  11  5  After  1  5  6  0  4  2  5  3  1  State the null hypothesis if traffic department wants to test whether the modification reduces the number of traffic accidents in Central.   Continue from part a, state the corresponding alternative hypothesis of the test.   Continue from part a, calculate the test statistics of the test.   Continue from part c, what is the critical value of the test if the significant level is 1%?   According to the test, is it reasonable to conclude that the modification reduced the number of traffic accidents?

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Read the following and answer the questions. 

Traffic department wants to know if automobile accident is a very serious problem in Central compared to other districts in Hong Kong. Nine intersections in Central have been chosen at random. The number of accidents at those intersections has been recorded for three months. The average number of accidents at an intersection in Hong Kong in the past three months is 3. 

 

The number of accidents at the chosen intersections in Central: 

11 

  1. Calculate the mean number of accidents in Central.  
  2. Calculate the sample standard deviation for the number of accidents in Central.  
  3. State the null hypothesis if traffic department wants to test whether automobile accident is a very serious problem in Central compared to other districts in Hong Kong.  
  4. Continue from part c, state the corresponding alternative hypothesis of the test.  
  5. Continue from part c, calculate the test statistics of the test.  
  6. Continue from part e, what is the critical value of the test if the significant level is 5%?  
  7. According to the test, is automobile accident a very serious problem in Central compared to other districts in Hong Kong?  

 

 

A team of experts claims that a modification in the type of light will reduce these accidents. The lights at the chosen intersections in Central were modified. The number of accidents before and after the modification has been recorded.  

 

Before 

11 

After 

  1. State the null hypothesis if traffic department wants to test whether the modification reduces the number of traffic accidents in Central.  
  2. Continue from part a, state the corresponding alternative hypothesis of the test.  
  3. Continue from part a, calculate the test statistics of the test.  
  4. Continue from part c, what is the critical value of the test if the significant level is 1%?  
  5. According to the test, is it reasonable to conclude that the modification reduced the number of traffic accidents?  

 

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