COSC 101: Exam 1 Practice Problem Solutions

Problem #4 Solution

years = int(input("years: "))
pop = 307357870
secs = years * 365 * 24 * 60 * 60
births = secs / 7
deaths = secs / 13
newimmigrants = secs / 35
print ( int(pop + births - deaths + newimmigrants) 

Problem #5 Solution

problem description

N = int(input("What is N? "))
sum = 0
for i in range(N):
    sum = sum + (i+1)
print(sum) 

Problem #6 Solution

problem description

N = int(input("What is N? "))
sum = 0
for i in range(N):
    sum = sum + (i+1)
    print(sum)

Problem #7 Solution

problem description

knuts = int(input("How many knuts? "))
sickles = knuts // 29
if sickles > 0:
    galleons = sickles // 17
    # compute the remaining sickles
    sickles = sickles % 17
    if galleons > 0:
        print ("There are",int(galleons),"galleons.")
    if sickles > 0:
        print ("There are",int(sickles),"sickles.")

Problem #8 Solution

problem description

i = int(input('gimme an int: '))
if i % 2 == 0:
    print('even')
else:
    print('odd')
if i % 4 == 0 and i % 7 == 0:
    print('divisible by 4 and 7')

Problem #9 Solution

problem description

numdays =  int(input("How many days did it snow? "))
totalsnow = 0
maxsnow = 0
for i in range(numdays):
    snowamt = int(input("Enter snowfall amount: "))    
    totalsnow = totalsnow + snowamt
    if snowamt > maxsnow:
        maxsnow = snowamt

snowavg = totalsnow / 28.0 
print("The average snowfall per day is",snowavg,"cm.")
print("The maximum daily snowfall is",maxsnow,"cm.")

Problem #10 Solution

problem description

any odd value that is not 3 would hit assignment 1
the value 3 would hit assignment 2
any even value less than or equal to 10 would hit assignment 3
any even value greater than 10 would hit assignment 4

Problem #11 Solution

problem description

secs = int(input("What's the number of seconds (1-86400)? "))
hours = secs // (60*60) # integer division!
secs = secs - hours*60*60
mins = secs // 60  # again, integer division
secs = secs % 60
print (str(int(hours))+":"+str(int(mins))+":"+str(int(secs)))

Problem #12 Solution

problem description

principal = float(input("How much is the initial investment? "))
rate = float(input("What is the interest rate? "))
years = int(input("How many years to invest? "))
totinterest = 0.0

# in the print statements below, the \t is a tab character; it just helps with spacing.
# you could just use spaces, too, or anything else that spaces things out nicely.

print("Year\tTotal investment value\tInterest earned")
print("----\t----------------------\t---------------")
print(0,"\t",round(principal,2),"\t\t\t",round(totinterest,2))
for i in range(years):
    interest = principal * rate
    totinterest = totinterest + interest
    principal = principal + interest
    if principal < 10000: # extra tab needed for alignment
        print(i+1,"\t",round(principal,2),"\t\t\t",round(totinterest,2))
    else:                 # no extra tab necessary
        print(i+1,"\t",round(principal,2),"\t\t",round(totinterest,2))

Problem #13 Solution

problem description

# Wallis approximation to pi, version 1
# This version uses a for loop over pairs
# of terms in the product
terms = int(input("How many terms? "))
pi = 2.0
for pair in range(terms//2):
    num = 2 * pair + 2
    denom = 2 * pair + 1
    pi = pi * num / denom
    denom = denom + 2
    pi = pi * num / denom

print("The pi approximation is", pi)

# Wallis approximation to pi, version 2
# This version uses a for loop plus an
# if statement to adjust for odd/even terms
terms = int(input("How many terms? "))
pi = 2.0
for term in range(terms):
    if term % 2 == 0:
        num = term + 2
        denom = term + 1
    else:
        num = term + 1
        denom = term + 2
    pi = pi * num / denom

print("The pi approximation is", pi)

Problem #14 Solution

problem description

therange = 56-10
for i in range(therange+1):
    if (i+10) % 6 == 0:
        print(i+10)

Problem #15 Solution

problem description

# one possibility
n = int(input("What number to test for primality? "))
isprime = True
for i in range(2, n):	# really only need range(2, int(n**0.5)+1)
    if n % i == 0:
        isprime = False
if isprime:
    print(n,"is prime")
else:
    print(n,"is not prime")

Problem #17 Solution

problem description

adj1 = input("Enter an adjective: ")
adj2 = input("Enter an adjective: ")
verb = input("Enter a verb (past tense): ")
prep = input("Enter a preposition: ")
anim = input("Enter an animal: ")
obje = input("Enter an object: ")

print("\nThe", adj1, anim, verb, prep, "the", adj2, obje+".")
print("The", adj1, anim, "was no longer", adj1+".")

Problem #18 Solution

problem description

import math
pi = math.pi

print("Please give me three numbers")
a = float(input("A: "))
b = float(input("B: "))
c = float(input("C: "))

cube_area = str(round(6 * b**2 , 2))
cube_volume = str(round(b**3 , 2))
print("If you have a cube with height B, it's surface"+\
      " area will be "+str(cube_area)+" and volume "+\
      str(cube_volume)+".")

circle_radius = round(c / 2 , 2)
circle_circumference = round(pi * c , 2)
circle_area = round(pi * circle_radius ** 2 , 2)
print("If you have a circle with diameter C, the radius 
    will be "+str(circle_radius)+', the circumference '+
    str(circle_circumference)+', and the area '+
    str(circle_area)+'.')

triangle_area = round((1/2) * b * a , 2)
print('If you have a triangle with height A and base B,'+\
      ' the area will be'+str(triangle_area)+'.')