The first midterm exam will be in class (usual place and time) on Friday, February 24, 2006. This page has some guidance about that test.
Bring the tear-out orangish sheet from the middle of the textbook, or (if you don't want to tear it out), download and print out the PDF of the same thing from the textbook website.
Bring one standard size (8.5 by 11 inches) paper with formulas or other notes that you made yourself (you may use both sides of the sheet).
You may use a non-graphing, non-programmable calculator for the exam. Fancier calculators, computers or other electronic devices are not permitted.
Example Question. The variance is the square of the standard deviation.
There will be a penalty for guessing. The Right answer counts the number of points for the question. The wrong answer counts minus that number of points. No answer counts zero points. Circling both answers counts zero points.
This means completely clueless guessing should, on average, get zero points. Informed guessing (with better than even chance of getting the right answer) is worth while.
The directions will say: circle the one most correct answer for full credit. You may circle more than one answer, but each incorrect answer is penalized.
Example Question. The following are measures of center of a distribution.
There will be a penalty for guessing. The right answer counts the number of points for the question. Each wrong answer counts minus that number of points divided by the number of wrong answers. No answer counts zero points. Circling all the answers counts zero points.
Suppose the example above counts 3 points. Then circling the correct answer (d) counts 3 points. Circling any other answer counts minus 1 point. So circling answers (b) and (d) and no others would count 3 − 1 = 2 points.
These look like multiple choice but are not.
The directions will say: circle the one most correct answer. Do not circle more than one answer. You must show how you got the answer. No explanation, no credit.
Credit is not given for circling the right answer but for showing how to get the right answer. The only point of the multiple answers is to make the calculation easier. You only need enough accuracy to say which one is right.
Example Question. Suppose heights of adult men are normally distributed with mean 1.7 meters and standard deviation 0.2 meters. What is the x such that 30% of adult men have height less than x?
Solution. This is a general (not standard) and backward (not forward) problem. The problem is solved in two steps
Step 1. The z such that 0.3 of the standard normal curve is less than z is found by finding 0.3 in the middle of the table and seeing what z it corresponds to.
The following row in the table
.00 .01 .02 .03 .04 .05 .06 .07 .08 .09
- 0.5 | .3085 .3050 .3015 .2981 .2946 .2912 .2877 .2843 .2810 .2776
has the 0.3000 somewhere between the highlighted numbers. So the corresponding z is somewhere between − 0.52 and &minus 0.53, say − 0.525 (although it doesn't matter to the accuracy we need here).
Step 2. Unstandardize using x = μ + σ z (being careful because z is negative here).
So the answer to circle is (b).