MONT 105S, Spring 2009

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Solutions for Review sheet for midterm

Practice Problems
The following problems are intended to help you study for the exam.

1)Given these boolean variables:

x = true, y = false, z = true

i)  x and (y or z)

Answer:	True

ii) (not x) or  (not(y and z))

Answer:	True

iii) y or (x and not z)

Answer:	False

Prompt the user to input a number.
Input the number from the keyboard
If the number is less than 100, write:
	XX is a low number.
where XX refers to the number inputted by the user.
Otherwise, write:
	XX is a high number.

#Program lowOrHigh.py
number = input("Enter a number: ")
if number < 100:
	print number, "is a low number."
else:
	print number, "is a high number."

3) a) What is the value of sum after the execution of the following code?

	sum = 0
	counter = 1
	while counter < 6:
		sum = sum + 2 * counter
		counter = counter + 1
	print sum

b) Re-write the above code using a for loop instead of a while loop

	sum = 0
	for counter in range(1, 6):
		sum = sum + 2*counter
	print sum
	

4) What is the output of the following code fragment (mySentence and partial are both strings)?

	mySentence = "It was a dark and stormy night"
	partial = mySentence[10:13]
	print partial	

Answer: ark

• a)

           #Program Error1
           number = raw_input("Please enter a number: ")
           number = number/2.0
           print number
           
   Answer: raw_input( ) is used to input a number.  It should be input( )
  

  
  

• b)

          #Program Error2
          response = raw_input("Do you like chocolate? ")
          if response == "yes":
              print "Me too!"
          	else:
              	print "That's too bad."
           
  Answer: else should be indented by the same amount as if
  

  
  

• c)

           #Program Error3
           secret = "mont105S"
           response = raw_input("Enter the password: ")
           if response = secret:
           	print "Access granted."
           else:
           	print "Access denied.   
           
  Answer: The = in the conditional should be ==
  	Also, the end quote on the last print statement is missing.
  

  
  

• d)

           #Program Error4
           count = 0
           while count < 10
           	print count
           	count = count + 1
           
  Answer: The colon after the header of the while loop is missing.
  

	sum = 0
	count = 5
	while count <= 12:
		sum = sum + count
		count = count + 2

a) Fill in the following table for the values of count and sum each time through the loop (there may be more rows than you need in the table):

sum	count
0	5
5	7
12	9
21	11
32	13

b)Write a for loop that does the equivalent of the above loop.

sum = 0
for count in range(5, 13, 2):
    sum = sum + count

7. Consider the following Python code:

        sum = 0
        for i in range(1, 5):
              sum = sum + i
        print sum

Answer: 10

  8. Fill in/write the necessary code for the following decision tree.

#program catCheck.py
answer = raw_input("Do you have a cat? ")
if answer == "yes":
	answer = raw_input("What kind is it? ")
	if answer == "Siamese":
		print "Good choice!"
	elif answer == "Tiger":
		print "Another good choice."
	elif answer == "Calico":
		print "I have never had that kind."
else:
	print "You should get one."

9. Fill in the necessary code to fill in the depositList list with deposit amounts entered by the user. You should keep track of the sum of all the deposits made, so that the print statement at the end of the program makes sense. You can assume there are exactly 100 deposits made.

#Program deposit.py
sum = 0
depositList = [ ]

for i in range(100):
    deposit = input("Please enter amount of deposit: ")
    depositList.append(deposit)
    sum = sum + deposit
    
print "The sum of the deposits: ", sum