stats 203 practice midterm solutions

stats 203 practice midterm solutions - Student Name:...

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Student Name: Student Number: Faculty of Science MIDTERM EXAMINATION Mathematics 203 Principles of Statistics I Friday, October 22nd Answer directly on the test (use front and back if necessary). Calculators are allowed. One 8.5” × 11” sheet of notes is allowed. Language dictionaries are allowed. There are 6 pages to this exam and the total number of marks for the exam is 100. There is a bonus question at the end that is worth up to 10 extra points for a correct answer. It does not hurt your score to skip the bonus question. 1
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Question 1: (10 points) (a) Take these six statistical measures and put them in the correct column as to what they measure. (6 points) Mode IQR (Inter-quartile range) Variance Mean Range Median Two points for each correct block Flled (order does not matter). Center Spread Mode Range Mean Variance Median IQR (b) Which measure of center is least robust to outliers? (2 points) No explanation necessary. Mean, 4 points, no partial credit. (c) Which measure of spread is most robust to outliers? (2 points) No explanation necessary. IQR, 4 points, no partial credit. 2
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Question 2: (20 points) Say a company tests two treatments for an illness. In trial No. 1, treatment A cures 20% of its cases (40 out of 200) and treatment B cures 15% of its cases (30 out of 200). In trial No. 2, treatment A cures 85% of its cases (85 out of 100) and treatment B cures 75% of its cases (300 out of 400). (a) What is the probability that a randomly selected person who received treatment A from trial No.1 was cured? (4 points) 40/200 = 20% (4 points, 1 point for wrong attempt) (b) What is the probability that a randomly selected person who received Treatment B was cured (i.e. pooling the patients from the two trials) ? (4 points) 330/400 (4 points, 1 point for wrong attempt) (c) What is the probability that a randomly selected person who received Treatment A was cured (i.e. pooling the patients from the two trials) ? (4 points)
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stats 203 practice midterm solutions - Student Name:...

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