Download CS 235 Quiz #2: Truth Tables, Loops, Functions, and Lists and more Quizzes Computer Science in PDF only on Docsity!
COSC 235 Spring 2007
Quiz
Please read each question carefully and be sure to give complete answers. Good luck!
- (1 pt.) What is your name? ___________________________________________
- (8 pts.) Complete the following truth table: p q r p and q not r (p and q) or (not r) T T T T T F T F T T F F F T T F T F F F T F F F
- (12 pts.) Write a while- loop to do each of the following: a) Find the sum of the first n counting numbers: 1 + 2 + 3+ … + n b) Find the sum of the first n even numbers: 2 + 4 + 6 + … + 2n c) Count how many times 5 can be subtracted from a number x before the number is negative.
- (8 pts) Rewrite the following pre-test loop using Python’s “post-test” loop idiom. cash = - 1 while cash < 0: cash = input(“Enter a positive number: “) if cash < 0: print “Try again”
- (16 pts.) Write two functions die() and dice() that model a pair of dice. die() should generate a random number, from 1 to 6 inclusive for the value of a roll of a single die. dice() should use die() to generate a pair of random number corresponding to the roll of a pair of dice. It should return the values generated as a pair and should display the values, their sum, and, if appropriate a message “You rolled doubles!”. For example: >> d1, d2 = dice() Your rolled doubles. You rolled 6 and 6, a total of 12. >> d1, d2 = dice() You rolled 3 and 5, a total of 8. Note: This function both returns and displays values!
- (8 pts.) The Fibonacci sequence starts 1, 1, 2, 3, 5, 8, …. That is, each number is the sum of the two previous numbers. Thus, thee next number is 5 + 8 or 13. Write a function that returns the n th Fibonacci number. For example, fib(6) would return 8. The code on the next page is an incomplete class definition for a class Tests that records the test grades for a course. Use this code to answer the following questions.
- (3 pts.) In the appropriate space, add a docstring of your choosing to the class.
- (8 pts.) In the appropriate space, write a method average that calculates and returns the grade average for the tests taken in a course. Your code should return 0 in no tests have been recorded and the arithmetic mean otherwise.
- (12 pts) In the space below the code, give code to a) create two instances of tests, COSC235 and MATH b) recorded the grades 98, 92, and 96 for COSC c) recording the grades 90 and 92 for MATH d) display the second recorded grade for COSC e) display the average for each course f) display the highest grade recorded for MATH
Attached is the code for the preceding problems
class definition
class tests: ##constructor def init(self): self.grades = []
record a grade
def record(self, score): self.grades.append(score)
return a grade based on it position in the list
def report(self, number): return self.grades[number - 1]
return the current average grade
utilitiy function
def listMax(self, lst): x = lst[0] for i in lst: if x < i: x = i return x
find the highest grade
def maxGrade(self): return self.listMax(self.grades) Pledged: ________________________________________________________________
