statisics HW
twex9999
_statisticshomework_f14.docxHomework - ENGR 102B
Individual Assignment: Data and Statistics
Due on the dropboxdue date via D2L
(A Word document, pdf, or scan of hand-written homework are all acceptable formats)
1. (30pts) An ENGR 102B class has forty student enrolled in it. The exam scores for six students within this class are 86, 97, 76, 83, 92, and 55(looks like that last student didn’t study hard enough!). For this data sample, calculatethe following (and show all of your work):
a. The mean
b. The median
c. The range
d. The unbiased sample variance
e. The standard deviation
2. (10pts) Your boss puts you in charge of collecting data that shows the costs of the five major components and subassemblies that go into manufacturing a piece of equipment. What type of data display chart would you select to most effectivelyconveythis information to your boss, and why would that type of chart be a good choice?
3. (25 pts total) A semiconductor manufacturing company is experiencing difficulties with devices that are rejected because they fail to work properly after being manufactured. Data are collected, and it is found that the errors causing the defective semiconductors can be categorized into seven different classes:
|
Cause of Failure |
Number of Occurrences |
|
Contamination |
134 |
|
Corrosion |
207 |
|
Doping |
33 |
|
Oxide defect |
92 |
|
Silicon defect |
122 |
|
Metallization |
145 |
|
Miscellaneous |
27 |
(15 pts) First, construct a Pareto Chart to show failure types in descending order by their frequency. (You can use another application such as Excel to construct your chart and paste it here, if you like, or you can draw this by hand.)
(10 pts) Then, identify the categories that make up 80% of the cases of failure so that you can advise the manufacturing company where to concentrate their efforts to improve. In other words, what are the specific categories that account for 80% of the failures?
4. (10 pts) Fill in the blanks: The number of hours it takes for a certain metal part to wear out is assumed to be from a population with a normal probability distribution with a mean of 1,200 hours and a standard deviation of 130 hours. If this is true, then approximately two-thirds, or 68 percent, of the parts are predicted to wear out between _______ and _______ hours of operation.
5. (25pts) Suppose that the scores on a mathematicsaptitude test are normally distributed. If the test results have a mean score of 80points and a standard deviation of 10 points, what is the probability that a student from this population scored 90 points or lower on this particular test? (Hint: How many standard deviation above the mean is the score for 90? If you know this, you can find the area covered by the normal distribution.)
