Assessment 1 - Assignment
Unit: STA101 – Statistics for Business
Total Marks:This assignment is worth 40 marks (40 % of the total marks in the unit).
Instructions:
•Students are required to cover all stated requirements.
•Your answer must be both uploaded to Moodle in word file and handed over a printed copy.
•You need to support your answers with appropriate Harvard style references where necessary.
•Include a title/cover page containing the subject title and code .
Each of the following question worth 10 marks, please answer all of them. If needed please use Harvard referencing style. There is no word limit, but it is necessary that you provide answers with explanations.
Question 1: (10 marks)
Given the following sample data:
x | 420 | 610 | 625 | 500 | 400 | 450 | 550 | 650 | 480 | 565 |
y | 2.80 | 3.60 | 3.75 | 3.00 | 2.50 | 2.70 | 3.50 | 3.90 | 2.95 | 3.30 |
1. Calculate the covariance and the correlation coefficient |
2. Comment on the relationship between x and y |
3. Determine the least squares line. |
4. Draw the scatter diagram and plot the least squares line. |
Question 2: (10 marks)Consider the following Excel regression of perceived sound quality as a function of price for 27 stereo speakers.
a. Is the coefficient of Price significantly different from zero at α = .05?
b. What does the R2 tell you?
c. Given these results, would you conclude that a higher price implies higher sound quality?
Regression Statistics | |
R Square | 0.01104 |
Standard Error | 4.02545 |
Observations | 27 |
Statistic | Coefficients | Std Error | t Stat | P-value | Lower 95% | Upper 95% |
Intercept | 88.4902 | 1.67814 | 52.731 | 0.0000 | 85.0340 | 91.9464 |
Price | −0.00239 | 0.00453 | −0.528 | 0.6019 | −0.01172 | 0.00693 |
Question3: (10 marks)After researching cysts of a particular type, a doctor learns that out of 10,000 such cysts examined, 1,500 are malignant and 8,500 are benign. A diagnostic test is available which is accurate 80% of the time (whether the cyst is malignant or not). The doctor has discovered the same type of cyst in a patient.
Question4: (10 marks)
Below are monthly rents paid by 30 students who live off campus:
730 | 730 | 730 | 930 | 700 | 570 |
690 | 1,030 | 740 | 620 | 720 | 670 |
560 | 740 | 650 | 660 | 850 | 930 |
600 | 620 | 760 | 690 | 710 | 500 |
730 | 800 | 820 | 840 | 720 | 700 |
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