Online Homework Syste

Online Homework System

Assignment Worksheet
4/05/15 - 2:03 PM 

Name:

____________________________

Class:

CVEN9710 Management of Risk - 2015

Class #:

____________________________

Section #:

____________________________

Instructor:

Steven Davis

Assignment:

Statistical Inference and Fault and Event Trees

Question 1: (2 points)

A confectionery manufacturer grabs 5 packets of lollies from the production line, opens them up and counts how many lollies are inside each bag. The results are given in the table below.

Determine the 98% confidence intervals for both the mean and variance of the number of lollies in bags coming from this production line. All answers should be to the nearest 1 decimal place.

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Question 2: (1 point)

A confectionery company normally produces bocks of chocolate that average 250 grams in size. Management have decided to reduce the average block size down to 200 grams. This requires new moulds and adjustments to the machine that squirts the chocolate into the moulds. The chocolate squirting machine does not have a dial controlling the amount squirted into each mould. Instead the mechanics need to use a trial and error process of adjusting the pressure of the chocolate and the timer for the valve. Experience has shown that the standard deviation of the amount of chocolate squirted each time is 4 grams. How many test blocks of chocolate need to be made after each adjustment if management want to be 90% sure that the mean amount of chocolate squirted into each block is accurate to within 1.5 grams.

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Question 3: (2 points)

You have a contract to mark exam papers for a statistics school. They send you a box containing several bundles of exam papers. According to the contract you are paid by the bundle and that the average number of papers in all bundles sent out for marking is 61. The bundles feel a bit heavy to you so you count the number of papers in each bundle. These numbers are given in the box below.

Your contract states that any dispute over the number of papers must be based on a statistical test with a significance level of 5%. You decide to test the hypothesis that the population average for the number of papers in a bundle is greater than 61.

What is the value of the statistic that you calculate from the data? (3 decimal places) ____________

What is the boundary for the critical region for this test (from the relevant table)? (3 decimal places)____________ (Your sign convention for both answers should be such that this second answer is positive)

Based on the results of the test you: