Download Marking Scheme - Department of Computer Science and Information

Department of Computer Science and Information Systems
Birkbeck College, London
Introduction to Programming
IN-LAB-TEST MAY_PYTHON VERSION MARKING SCHEME
6th May 2016
This test is closed book. Access to the internet is not allowed except for the uploading
of a single file containing your program to Moodle. Mobile phones, calculators,
laptops, USB memory sticks and other electronic devices are not allowed.
Instructions
Create a new folder in your disk space with the name InLabTestMay.
Launch the Python Integrated Development Environment IDLE. Begin with the Start
icon in the lower left corner of the screen. If you are in a DCSIS laboratory then
follow the sequence
Start -> All Programs -> Python 3.4 -> IDLE (Python GUI)
A window with the title Python 3.4.1 Shell should appear.
If you are in one of the ITS laboratories MAL 109, MAL 457 or MAL 458, then
follow the sequence
Start -> All Programs -> Departmental Software -> Computer Science ->
Python 3.4 -> IDLE (Python 3.4 GUI – 64 bit)
A window with the title Python 3.4.4rc1 Shell should appear.
In the Shell click on File. A drop down menu will appear. Click on New File. An
Editor window with the title Python 3.4.1:Untitled (DCSIS) or Untitled (ITS) should
appear.
In the Editor, click on File, and then in the drop down menu click on Save As… . A
window showing a list of folders should appear. Find the folder InLabTestMay and
double click on it. In the box File name at the bottom of the window type
InLabTestMay.py, and then click on the button Save in the lower right corner of the
window. The title of the Editor should change to show the location of the file
InLabTestMay.py.
At the end of the test upload the single file InLabTestMay.py to the
Assignment InLabTestMay in Moodle.
There are three questions. Question 1 is worth 40 marks, Question 2 is worth 30
marks and Question 3 is worth 30 marks. Answer all three questions.
Introduction to Programming in-laboratory test May 2016 Marking Scheme Page 1
Plagiarism Warning
Students are reminded that the Department and the College apply a very strong policy
in cases of plagiarism. Helping other students or taking advantage of help from other
students during the test are considered to be plagiarism.
Any excessive similarities between the work of different students will be carefully
checked. The lightest penalty in case of plagiarism for those involved will be a mark
of 0 for the whole test.
Students caught during the test communicating with others by any means will be
asked to leave the laboratory immediately and will be given a mark of 0.
The following list of Python statements may contain entries which can be adapted as
necessary to form parts of the answers to this test.
## This comment is important because it provides information necessary for
# understanding the purpose of this file.
# @param describe the parameters
# @return describe the nature of the returned value
# @author John Doe
# @version 6.5.16
#
if x == 4 :
print("x:", x)
for i in range(5) :
print(i)
for letter in string :
print(letter)
from math import sqrt
x = int(input("Enter an integer: "))
i = len("string")
ch = "string"[2]
string47 = str(47)
def newFunction(n) :
print(2*n)
return 2*n
Introduction to Programming in-laboratory test May 2016 Marking Scheme Page 2
Question 1 (40 marks)
Place a short comment at the head of the file InLabTestMay.py to identify the purpose
of the file, the author and the date. Write a function with the following header
def salary() :
The function salary prints out the prompt
Please enter your salary:
and then obtains the salary from the keyboard. The salary is returned by the function
salary in the form of a floating point number. Place a short explanatory comment
immediately before the definition of salary.
Make one call to salary to test the code. Use print to display the result of the call in
the Shell. Transfer the result “by hand”, i.e. by manual typing, from the Shell to a
comment placed after the call to salary. In the comment write out the number input to
salary at the keyboard and the corresponding number returned by salary and printed in
the Shell.
Marking Scheme for Question 1
1. Comment at head of file (10 Marks). Comment for salary (5 marks). Total 15
marks.
2. The code is implemented in a reasonable way, ignoring minor syntax errors such as
a missing : or incorrect indentations (15 marks), compiles and runs correctly (5
marks). Total 20 marks.
3. One call correctly reported in the comment. Here “correct” means that the output
of the implemented function is correctly described. It does not necessarily mean that
the function is a correct answer to the question. 5 marks.
Question 2 (30 marks)
Write a function with the following header
def numberOfChildren() :
The function numberOfChildren prints out the prompt
Please enter the number of your children:
and then obtains a number n from the keyboard. If n is strictly negative, then
numberOfChildren prints out the error message
Error: a number greater than or equal to 0 is required.
and then repeats the prompt. This cycle is repeated until a number greater than or
equal to 0 is entered. This number is returned in the form of an integer. Place a short
explanatory comment immediately before the definition of numberOfChildren.
Introduction to Programming in-laboratory test May 2016 Marking Scheme Page 3
Make one call to numberOfChildren to test the code. Provide as input to
numberOfChildren three integers strictly less than 0 followed by one integer greater
than or equal to zero. Use print to display the result of the call in the Shell. In a
comment placed after the call to numberOfChildren i) list the sequence of integers
input during the call; ii) confirm or otherwise that the error message was printed out
for each negative input; iii) confirm or otherwise that the final integer in the input
sequence was returned by numberOfChildren. It is not necessary to write out the error
message in the comment.
Marking Scheme for Question 2
1. Comment for numberOfChildren. 5 marks.
2. The function numberOfChildren is implemented in a reasonable way, ignoring
minor syntax errors such as a missing : or incorrect indentations (15 marks),
compiles and runs correctly (5 marks). Total 20 marks.
3. One call correctly reported in the comment (see the marking scheme for Qu. 1). 5
marks.
Question 3 (30 marks)
A non-governmental organization provides financial assistance for families. The
formula is as follows:
If the annual household income is greater than or equal to $30,000 and strictly less
than $40,000 and the household has at least three children, then the amount is $1,000
per child.
If the annual household income is greater than or equal to $20,000 and strictly less
than $30,000 and the household has at least two children, then the amount is $1,500
per child.
If the annual household income is strictly less than $20,000, then the amount is
$2,000 per child.
In all other cases the amount is $0.
Write a function with the following header
def assistance(s, nc) :
The argument s is the salary in dollars and the argument nc is the number of children.
The function assistance returns the value specified by the above formula in the form
of an integer. Place a short explanatory comment immediately before the definition of
assistance. It is not necessary to include the formula in the comment.
Make five calls to assistance to test the code. Use print to display the result of each
call in the Shell. Copy the results by hand from the Shell to a comment following the
five calls to assistance. The order of the results in the comment should be the same as
the order of the calls by which they were produced.
Introduction to Programming in-laboratory test May 2016 Marking Scheme Page 4
Marking Scheme for Question 3.
1. Comment for the function assistance. 5 marks.
2. The function assistance is implemented in a reasonable way, ignoring minor syntax
errors such as a missing : or incorrect indentations (15 marks), compiles and runs
correctly (5 marks). Total 20 marks.
3. One mark for each call correctly described in the comment (see Qu. 1). Total 5
marks.
Introduction to Programming in-laboratory test May 2016 Marking Scheme Page 5