# STAB22H3 Midterm: STAB22H3 Midterm 2008 Fall SolutionExamPremium

12 pages68 viewsFall 2018

Department

StatisticsCourse Code

STAB22H3Professor

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MidtermThis

**preview**shows pages 1-3. to view the full**12 pages of the document.**University of Toronto Scarborough

STAB22 Midterm Examination

October 2008

For this examination, you are allowed one handwritten letter-sized

sheet of notes (both sides) prepared by you, a non-programmable,

non-communicating calculator, and writing implements.

This question paper has 12 numbered pages; before you start,

check to see that you have all the pages. There is also a signature

sheet at the front and statistical tables at the back.

This examination is multiple choice. Each question has equal

weight. On the Scantron answer sheet, ensure that you enter your

last name, ﬁrst name (as much of it as ﬁts), and student number

(in “Identiﬁcation”).

Mark in each case the best answer out of the alternatives given

(which means the numerically closest answer if the answer is a

number and the answer you obtained is not given.)

Before you begin, check that the colour printed on your Scantron

sheet matches the colour of your question paper. If it does not,

get a new Scantron from an invigilator.

Also before you begin, complete the signature sheet, but sign it

only when the invigilator collects it. The signature sheet shows

that you were present at the exam.

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1. There are two sets of numbers. Set A is 5, 5, 5, 5. Set B is 4, 5, 6, 7. Without doing any calculations,

what can you say about the standard deviations of the two sets of numbers?

(a) Sets A and B have about the same standard deviation.

(b) Set B has a smaller standard deviation.

(c) The only way to compare the standard deviations is to calculate them.

(d) * Set A has a smaller standard deviation.

2. What is the median of the values 7, 3, 0, 1, 6?

(a) 3.4

(b) * 3

(c) 6

(d) 0

3. A stringing machine is a device for adjusting the tension of strings in a tennis racket. Some tennis

players ask for a string tension of 65 pounds. The actual tension produced by the machine for the

rackets belonging to these players varies according to a normal distribution with mean 65 pounds

and standard deviation 2 pounds. Use this information to answer this question and the 2 following

questions.

What proportion of rackets (belonging to players asking for a string tension of 65 pounds) will have a

string tension of 67.5 pounds or more?

(a) 0.00

(b) about 0.50

(c) 1.00

(d) 0.89

(e) * 0.11

4. Using the information in Question 3, what proportion of rackets (belonging to players asking for a

string tension of 65 pounds) will have a string tension between 64 pounds and 67.5 pounds?

(a) * 0.59

(b) 0.89

(c) 0.11

(d) 0.70

(e) 0.31

5. For all rackets (belonging to players asking for a string tension of 65 pounds), there is a value xsuch

that 20% of rackets will have an actual string tension less than xpounds. What is x?

(a) 60.9

(b) 69.1

(c) 66.7

(d) 65

(e) * 63.3

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6. Below is a comparison of scores in a spatial-temporal reasoning test for four groups of children. Higher

scores indicate superior reasoning. Use this information for this question and the following one.

Whichof the following is true?

(a) * The range and IQR for group C are both smaller than the corresponding measures for group B.

(b) More than 75% of those in group C scored higher than the best child in group A.

(c) Fewer than half of the children in group A scored above 0.

(d) The distribution of scores in group A is right skewed.

7. Using the information in Question 6 above, which group has a right-skewed distribution of scores?

(a) group A

(b) group D

(c) * group B

(d) group C

8. In a chemical procedure called diﬀerential pulse polarography, a chemist measured the peak current

produced (in microamperes) when a solution containing a given amount of nickel is used. A scatterplot

showing the peak current against amount of nickel (Ni), together with the least-squares regression line,

is shown below. Use this information for this question and the question following.

What is the correlation between peak current and amount of nickel? Choose the best alternative from

those given.

(a) * 0.99

(b) -1.00

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