a) (10 points) 3 points for the formula: Pi
02(sin(x))5dx. 5 points for
the antidifferentiation and 2 points for the answer.
b) (4 points) 2 points for the correct integrand and 2 points for the correct bounds on the definite integral.
| Problem | #1 | #2 | #3 | #4 | #5 | #6 | #7 | #8 | Total |
|---|---|---|---|---|---|---|---|---|---|
| Max grade | 12 | 14 | 12 | 10 | 14 | 12 | 14 | 12 | 93 | Min grade | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 13 | Mean grade | 8.35 | 7.92 | 4.86 | 5.66 | 5.58 | 7.99 | 7.57 | 3.86 | 51.79 | Median grade | 9 | 7 | 4 | 7 | 4 | 10 | 8 | 1 | 53 |
Numerical grades will be retained for use in computing
the final letter grade in the course. Students with grades of D or
F on this exam should be very concerned about their likely success in
this course. Indeed, students with low grades should evaluate the
amount of time and effort they can devote to this course as
part of their entire plan of work for the balance of the
semester. Such students may wish to drop this course or drop
another course in order to increase their chances of success in what
remains. I strongly recommend considering such actions.
Class attendance and watching the instructors do
problems is not adequate practice. Individual time and effort must be
given.
We will continue to use improper integrals, estimation techniques,
integration by parts, and familiarity with functions and with
algebraic manipulation a great deal in this course, and much of what
we will do is important to your later technical education and
practice. Please don't waste your time and effort with false
expectations. I want students to be successful and will work
diligently to help this occur, but I don't want to deceive them.
Here are approximate letter grade assignments for this exam:
| Letter equivalent | A | B+ | B | C+ | C | D | F |
|---|---|---|---|---|---|---|---|
| Range | [80,100] | [75,79] | [65,74] | [60,64] | [50,59] | [45,49] | [0,44] |
Minor errors (missing factor in a final answer, sign error, etc.) will be penalized minimally. Students whose errors materially simplify the problem will not be eligible for most of the problem's credit.
Problem 1 (12 points)
2 points for setting up the pieces in the partial fraction
expansion. 2 points for getting an equation relating the top to the
constants in the pieces. 3 points for correct solution of this
equation. 3 points for antidifferentiation. 2 points for the answer (1
of these for using ln properties to verify the displayed result).
Problem 2 (14 points)
a) (10 points) 3 points for the formula: Pi02(sin(x))5dx. 5 points for
the antidifferentiation and 2 points for the answer.
b) (4 points) 2 points for the correct integrand and 2 points for the
correct bounds on the definite integral.
Problem 3 (12 points)
This is a force·distance problem. Modeling the force (the
weight of the bucket) is worth 5 points. This should be a linear
function: A+B(Variable). Also
this function should be at least 1 in the variable's interval (the
student is advised that the weight of bucket+water is at least 1
pound). The limits of integration should be the length that the bucket
is raised: 2 points. The distance part is dVariable and earns 2
points if the limits of integration are correct.
3 points remain for the integration and answer (which is worth 1 of
the 3 points). A student's answer is eligible for these three
points if the function being integrated is linear, not constant, and
positive everywhere in the interval of integration whose length must
be the length the bucket is lifted, otherwise the student is not doing
the requested problem. An integration of any random function (a number
of people had quadratic integrands) on any random interval will not
earn credit.
Problem 4 (10 points)
Stating one useful substitution gets 4 points (2 points if the
dx and x are not consistent!). Correctly
carrying out the substitution to get an antiderivative (including
substituting back to x's!) is 6 points.
Beginning a good integration by parts strategy also will earn 4
points, and then carrying it out can earn the remaining 6 points.
Problem 5 (14 points)
a) (3 points) The sketch should have a straight line segment
and a curve which
intersect at (0,0) and (1,Pi/2) for arcsin
and which
intersect at (0,0) and (1,Pi/4) for arctan. The curve
should be increasing and concave up for arcsin and
increasing and concave down for arctan. 1 point will be
deducted for each indicated item which is not correct up to a possible
3 points.
b) (9 points) A correct setup (definite integral and integrand) earns
2 points. 5 points for correct antidifferentiation, and 2 points for
evaluation.
Problem 6 (12 points)
6 points for correct integration by parts and getting the
antiderivative (4 points for the first u,v step and then 2 points for
the final antiderivative). 3 points for setting up an integral from 1
to a large number and substituting (1 of these points was earned for
writing the improper integral as a limit of a proper integral with a
parameter). 1 point for finding the limit correctly, and 2 points for
showing where L'H is used and using it correctly. Just "plugging in"
infinity in the antiderivative is not an acceptable
strategy!
Note No points were earned if the student ignored the
integral and applied L'H to the integrand and presented some related
result as the "solution". This is a totally different and much easier
problem. It is not the problem students were asked to solve.
Problem 7 (14 points)
a) (6 points) There should be seven terms, values of square root at
the appropriate x's, "weighted" appropriately (1/4/2/4/2/4/1), and
these should be multiplied by (6-0)/(6·3). The multiplier is
worth 1 point, the weights are worth 2 points, the appropriate x's are
worth 2 points, and square root appearing correctly is worth 1
point. No function evaluations need to be done. If the function in the
sum is only identified as "f" then the 1 point for square root is not
earned.
b) (8 points) Use of the second derivative graph to get some estimate
of the size of |f´´(x)| on [1,3] is worth 2
points. Use of the Trapezoidal Rule error term is worth 2
points. The correct N earns 1 point, and getting some correct
numerical error estimate is 1 point. A correct (interval!)
answer earns the last 2 points and this can only be earned with a
correct error estimate.
Comment Some answers confuse the estimate of the integral and
the error estimate. These are not the same.
Problem 8 (12 points)
2 points for trying the correct substitution (some multiple of
tangent); 1 point for getting the multiple correct; 1 point for
getting secant out of the quadratic term; 1 point for the correct dx;
1 point for getting to the integral of secant; 1 point for applying
integral of secant correctly; 3 points for getting back to x
correctly; 2 points for the correct answer (evaluating and using log
properties).
The student also could earn all points by evaluating the integral
correctly in the substituted variable (no student did this).
| Problem | #1 | #2 | #3 | #4 | #5 | #6 | #7 | #8 | Total |
|---|---|---|---|---|---|---|---|---|---|
| Max grade | 16 | 12 | 12 | 10 | 12 | 12 | 12 | 14 | 95 | Min grade | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | Mean grade | 11.44 | 8.66 | 6.73 | 3.03 | 2.29 | 4.63 | 4.95 | 8.44 | 50.14 | Median grade | 13 | 10 | 7 | 2 | 1 | 3 | 8 | 9 | 51 |
Numerical grades will be retained for use in computing
the final letter grade in the course.
Here are approximate letter grade assignments for this exam:
| Letter equivalent | A | B+ | B | C+ | C | D | F |
|---|---|---|---|---|---|---|---|
| Range | [80,100] | [75,79] | [65,74] | [60,64] | [50,59] | [45,49] | [0,44] |
Minor errors (missing factor in a final answer, sign error, etc.) will be penalized minimally. Students whose errors materially simplify the problem will not be eligible for most of the problem's credit.
Problem 1 (12 points)
a) (6 points) 2 points for horizontal; 4 points for the others (1
point off for each element which is tilted up where it should be down
or vice versa, and 1 point off if the elements do not vary correctly,
more or less tilt, as scanned horizontally: max of 2 off for "tilt"
errors) and max of 2 off for sign errors.
b) (2 point) one equilibrium solution and specification of the
constant with the right equation (so x=CONSTANT loses a point because it does
not describe a solution to the differential equation).
c) (8 points) 1 point for correct separation; 3 points for integration
(1 of these is for a correct "+C"); 2 points for use of the initial
condition; 2 points for solving for y as a function of x.
Problem 2 (12 points)
Use of the arc length formula: 1 point; correct computation of
f´(x) earns 2 points; 2 points for the correct integrand;
2 points for the change to sec(x); 2 points for integrating secant;
2 points for evaluating sec and tan at the endpoints; 1 point for the
final answer recognizing ln(1).
Note This is essentially problem 10 in section 8.1 of the
textbook.
Problem 3 (12 points)
a) (5 points) 2 points for the first and second derivatives; 2 points
for correct evaluation of the function value, and the first and second
derivatives; 1 point for final assembly of T2(x). ?????
b) (1 point) Earned for the answer. If the student gives a reasonable
polynomial as answer for a) this is earned by the value of the
student's polynomial at 5.
c) (6 points) The correct third derivative earns 2 points; estimation
of K in the correct way earns 2 points (selecting the correct endpoint
earns 1 of the 2 points but just selecting the incorrect endpoint
earns 0; the other point is earned for some reason why the correct
endpoint was selected); 2 points for putting everything together
(factorials, powers, etc.).
Problem 4 (10 points)
2 points for starting with a valid and relevant polynomial related to
ex; 2 points for correct substitution of -x2; 2
points for indicating multiplication of this polynomial by the
appropriate linear polynomial; 2 points for carrying out the
multiplication; 1 point for further algebraic expansion into standard
form (sum of constants times powers of x); 1 point for the answer. The
answer point is not earned if the polynomial does not have the
correct degree.
Problem 5 (12 points)
a) (6 points) Transforming the sequence to a form where
L'Hôpital's Rule could be used is worth 2 points; 1 point for
remarking on eligibility; 2 points for using L'Hôpital's Rule
(differentiation of the top and bottom); 1 point for the answer.
b) (6 points) 2 points for separating into two geometric series; 2
points each for the correct use of geometric series and the answer.
Problem 6 (12 points)
3 points for realizing or using the "key observation" that dropping
the square root increases the size of the fraction (using the other
part of the formula doesn't earn credit since it cannot be estimated
usefully); 3 points for showing that the infinite tail must be
estimated (here either a geometric series or a relevant [improper]
definite integral can be given); 3 points for estimating the infinite
tail by finding the sum of the relevant geometric series or with a
correct antiderivative; 3 points for using the sum and the
tabular information (or a correct integral!) to get a correct
answer. Merely asserting an answer is not sufficient to get credit
here (lots of data was supplied). Asserting that an infinite tail is
small because one or a few terms are small also earns no credit.
No credit will be given for a purely arithmetic approach to this
problem because this is a calculus course.
Problem 7 (12 points)
4 points for some evidence connecting the sum to the integral. One
acceptable item would be a picture similar to that displayed on the
answer sheet. An explicit inequality connecting the Nth
partial sum with a definite integral would also be acceptable. Also
useful would be mention of a relevant function decreasing. But
some evidence should be given.
4 points for evaluating a relevant definite integral. 4 points for a
correct answer with evidence showing that specific N is valid.
Students who use N in place of N+1 in an otherwise correct solution
will be penalized 2 points.
Problem 8 (14 points)
a) (8 points) 4 points for computing the ratio and correctly obtaining
a simple fraction (1 point is lost if the absolute value is missing);
3 points for obtaining the limit of the ratio; 1 point for the answer.
b) (6 points) 3 points for considering the case x=RIGHT END POINT. 1 of these 3 points is for
the answer, and 2 points for correct support of the answer.
3 points for considering the case x=LEFT END
POINT. 1 of these 3 points is for the answer, and 2 points
for correct supporting of the answer.
The final exam and course grades
B
Initial grading
Grading of the final exam was done on Friday, May 9, the day
following the exam. Each lecturer and recitation instructor graded the
same problems for all students. Certainly I should keep confidential
which problems I graded, so all I will say is that I don't want to
Taylor my thoughts any more, since I knew too much about Scottish
Mcthings.
Checking and regrading
I gave a final exam in another course soon after the grading day
mentioned above. I spent the three hours of that exam (and a bit more
time) checking the grading and the addition of all of "our" final
exams. I found a number of minor errors, of course, but unlike last
semester, found no errors which were large enough to change any
student's score substantially.
About the exam
The other instructors of the course and I all felt that the exam was
extremely straightforward. Indeed, when I discussed the exam
with a number of students after they finished, there was general
agreement that the problems all seemed familiar. Now you know that I
was not the principal author of the exam, or else you would have been
there for hours working on several fiendishly novel problems! I
believe that students who did not do well on this exam have a very
weak case for asserting they "know" the material.
The exam was taken
by 505 students on Thursday, May 8. The results, on a 200 point scale,
ranged from 0 to 200 (yes, the endpoints were achieved!). The median
was approximately 132. In our lecture, 70 students took the final
exam, and grades ran from 10 to 191, the median was 139, and the mean
was 126.60.
Final exam grades were converted from
numbers to letters using the "bins" displayed below. The alert reader
will note that these assignments are quite similar (multiply by 2) to
those used earlier for the first and second exams.
| Letter equivalent | A | B+ | B | C+ | C | D | F |
|---|---|---|---|---|---|---|---|
| Range | [175,200] | [165,174] | [150,164] | [135,149] | [110,134] | [100,109] | [0,99] |
Use of these grades
The final exam letter grades are given to allow individual lecturers,
who are responsible for reporting course grades, to align the
performance of their specific groups of students with the overall
performance of students in the course. Random chance may give one
lecturer a group of students with better or worse performance than the
overall population, and, indeed, specific scheduling requirements may
force specific subpopulations with different math preparation to
enroll in some lectures. The common final exam and grading are part of
the faculty's effort to assign appropriate course grades, with equal
grades for equal achievement.
Course grading
The information I had included the following: grades for the three
exams (two during the semester and the final), attendance information
(for the lecture, from the QotD, and for the recitation, as reported
by the peer mentors), textbook homework scores (reported by the peer
mentors), workshop grades (reported by Mr. Priyadarshi, although I did
some of the grading also), and quiz grades (reported by
Mr. Priyadarshi). This is a large mess of numbers but my electronic
friends handled the arithmetic with little strain.
I computed a number for each student essentially weighted as previously described. I then
assigned a tentative letter grade based on the breakpoints for the
exams. I examined each student's record to make sure that this process
had not distorted or misrepresented student achievement. I entered the
course grades into the Registrar's computer system on Monday,
May 12. I hope students will be able to see them soon.
If you have questions ...
Rutgers requests that I retain the final exams. Students may ask to
look at their exams and check the exam grading. These students should
send me e-mail so that a mutually satisfactory meeting time can be
arranged. Students may also ask how their course grades were
determined using the process I described. Probably e-mail will be
sufficient to handle most such inquiries.
Warning Students who officially passed the course are allowed to go on to Math 251. Those students with D's should think carefully about their progress in cumulative math courses and associated work.
Maintained by greenfie@math.rutgers.edu and last modified 5/12/2008.