Question

QUESTION 2

1. Boolean or "truth-valued" expressions are how we express conditions that control choices and repetition in computer languages. Consider the following Python Boolean expression, where variables alpha, beta, and gamma are of type Boolean:

   alpha and (beta or gamma)

   In any algebraic notation there are usually several different ways of writing the same expression. For instance, in integer arithmetic the value of expression '4 x (5 + 2)' is numerically equivalent to that of expression '(4 x 5) + (4 x 2)'.

   Which of the following Boolean expressions is logically equivalent to the one above?

   	a	(alpha or beta) and gamma
   	b	(alpha and beta) or (alpha and gamma)
   	c	(alpha and beta and gamma)
   	d	(alpha or beta) and (alpha or gamma)
   	e	not (not alpha)
   	f	(not alpha) and (not beta) or (not gamma)

QUESTION 4

1. This is a MULTIPLE ANSWER question, which means you are able to select one or more answers as being correct. Note that this does not necessarily mean that there are multiple correct answers. In any case, select all the answers you believe are correct.  (NB: There are no part marks awarded for multiple answer questions.)

   Consider the following block of Python code, where the variables blue, green and red have integer values.

   red = 0
   if blue < green:
       if green > 4:
           red = 5
       else:
           red = 6

   Consider the case when the code is executed and the first condition (i.e., blue < green) evaluates to False.

   In this case, which of the following statements is true?

   	a	Variable red will have the value 6 when the code terminates.
   	b	Variable blue will be less than variable green when the code terminates.
   	c	The second condition (i.e., green > 4) will be evaluated.
   	d	Variable red will have the value 5 when the code terminates.
   	e	Variable red will have either the value 5 or 6 when the code terminates.
   	f	Variable red will have the value 0 when the code terminates.
   	g	The second condition (i.e., green > 4) will not be evaluated.

QUESTION 5

1. This is a MULTIPLE ANSWER question, which means you are able to select one or more answers as being correct. Note that this does not necessarily mean that there are multiple correct answers. In any case, select all the answers you believe are correct.  (NB: There are no part marks awarded for multiple answer questions.)

   Consider the following Python predicate functions:

   def is_even(number):
       return number % 2 == 0

   def is_adult(age):
       return age >= 18

   After these expressions have been evaluated:

   john = 19
   terry = 18

   which of the following Python expressions evaluate to False?

   	a	(not is_even(terry)) or is_adult(terry)
   	b	is_even(terry) and is_adult(terry)
   	c	not (is_even(john) or is_adult(john))
   	d	not (is_even(john) and is_adult(john))
   	e	(not is_even(john)) and is_adult(john)
   	f	is_even(john) and is_adult(john)
   	g	(not is_even(john)) or is_adult(john)
   	h	(not is_even(john)) or (not is_adult(john))
   	i	is_even(terry) or is_adult(terry)

Answer 1

Answers:
Question 2)
   -> alpha and (beta or gamma) is equivalent to the expression
       (alpha and beta) or (alpha and gamma)
   -> it is a distributive law in boolean algebra.
   -> Option b is the correct answer.

Question 4)
   -> code:
       red = 0
       if blue < green:
           if green > 4:
               red = 5
           else:
               red = 6
  
   -> in above code if first if condition(blue < green) is not executed
   -> then the execution will not enter into that if condition.
   -> results in not modifying the value of variable red.
   -> so red will be equal to 0.(red = 0)
   -> finally the answers that are correct are:
  
       -> b) Variable blue will be less than variable green when the code terminates.
       Exp: so no modification in any variables.
           so blue variable value will be less than green variable when code terminates
      
       -> f) Variable red will have the value 0 when the code terminates.
       Exp: red value is not modified so red=0.
      
       -> g) The second condition (i.e., green > 4) will not be evaluated.
       Exp: Since first condition (blue<green) is false. Execution will not enter into inner if.
           This option is correct only if it also means that the innser else block will not executed.
  
   -> Correct Options for Question 4: b,f,g

Question 5)
   Consider the following Python predicate functions:
   def is_even(number):
       return number % 2 == 0

   def is_adult(age):
       return age >= 18

   After these expressions have been evaluated:
   john = 19
   terry = 18
   which of the following Python expressions evaluate to False?
  
   a. (not is_even(terry)) or is_adult(terry) : True
   b. is_even(terry) and is_adult(terry): True
   c. not (is_even(john) or is_adult(john)) : False
   d. not (is_even(john) and is_adult(john)) : True
   e. (not is_even(john)) and is_adult(john) : True
   f. is_even(john) and is_adult(john) : False
   g. (not is_even(john)) or is_adult(john) : True
   h. (not is_even(john)) or (not is_adult(john)) : True
   i. is_even(terry) or is_adult(terry) : True
  
   So Among all the above expressions: c,f are the expressions that are evaluated to false.
   So Answers are: c,f options.