1 The Exam

Exam 2 was given in class on Monday 1 April, 2019. The PDF of the exam is available here. You can find your individual responses on the submission page.

Stat	Exam 1	Exam 2
High	91.1%	93.1%
Median	80.6%	77.8%
Mean	78.6%	76.0%
Low	54.8%	52.2%
StdDev	9.6%	11.3%

A few notes that may not be evident from the uploads:

• The full-page Q11 was worth 4 points, though you’ll see a normalized (out of 1) score displayed if you missed points on it. Most points were for avoiding serious errors like failing to unlock what you lock or having some threads wait on more barriers than others.

  Comments of the kinds of errors I found (if any) in your Q11 solution are included in comments after your solution

• Q17.5 I dropped as ambiguous

• Q18 I did read all your work, but did not transcribe it. Half the points were for computing the block size, half for setting those bits to 1 in your answer.

2 Wrapping-up the Exam Experience

On or before Friday 12 April, you may submit an exam wrapper¹ to make up some of your lost points. This should be a plain-text document named exam2wrap.txt containing the following sections:

1. Preparation

   Reflect on how you prepared for the exam and how effective that was. Don’t limit yourself to the days immediately before the exam; how effective were you approaches to learning the material as the semester progressed as well?

2. Errors

   List each mistake you made on the exam, and explain the correct answer. If possible, also explain why you answered incorrectly: what confused you?

   If there are questions you got right, but based on the wrong reasoning, explain those too.

3. Plans

   Wrap-up this exam experience by planning what you’ll do differently in the future.

An example template might be:

Preparation
===========

I prepared for this exam by ...

I thought this was good/bad because ...


Errors
======

I missed Q17.4. The correct answer is ... because ...


Plans
=====

To improve my learning going forward, I plan to ...

If you do not submit a wrapper, your initial exam score will stand as your exam performance. If you do, that score can only go up, not down.

3 Key

Question	Key
Q1	(x>>(P+(P-3)*(L-1)))&((1<<(P-3))-1)
Q2	4
Q3	3
Q4	1
Q5	2
Q6	2
Q7	1
Q8	2
Q9	2
Q10	1
Q11	lock m1 between if and while; unlock m1 after primes[num_primes++] = i; and before next }
Q12	2
Q13	1 or 3 (can argue either way)
Q14	C(x, R(H(x)))
Q15	1
Q16	2
Q17	True True False True True False
Q18	0x1003F
Q19	False False True True

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1. See the teaching commons for a decent introduction to the idea of an exam wrapper.↩