Nathan Wing wrote:
Hello All,I've been racking my brain trying to figure out, what I imagine to
be, a very simple problem. I found the Intro to comp science MIT open
course (
http://ocw.mit.edu/OcwWeb/Electrical-Engineering-and-Computer-Science/6-00Fall-2007/CourseHome/index.htm)
and was working on the very first homework assignment. I was successful in
problem one, but having a hard time with problem two. Any help would be
greatly appreciated!
Regards,
Nathan
Here is the problem:
A wealthy donor has given MIT $500,000 to be used to pay the tuition of one
student every other year until the money runs out. Under the assumptions
that
a. The current annual tuition is $34,986 per year,
b. Tuition goes up at a rate of 4.1%/year, and
c. The principal will be invested so that it earns 5%/year,
solve the following problems:
1) Write a program that calculates and prints the total number of students
this gift will support and the tuition paid for the last student.
2)Write a program that calculates and prints the smallest gift (rounded to
the nearest $100) needed to support one student every other year for 100
years. In addition, print the number of iterations your program took to
arrive at the answer. Hint: you may want to use nested loops for this
problem.
my code that works for number 1:
#!/usr/bin/env python
#
#scholarship.py
#
#initialize values
year = 0
count = 0
money = 1000000.0 #fund amount
ctuition = 34986.0 #current tuition
rate = 1.041 # 4.1% annual increase on tuition
principle = 1.05 #5% annual interest accrued on fund
###calculations
while money > 0 and money >= ctuition: #while the fund has money and can
cover tuition
if year % 2 == 0: #if this is year 0 or every even year after year 0
money = money - ctuition
ftuition = ctuition
count += 1
ctuition = ctuition * rate
money = money * principle
year += 1
print "Total number of students aided: %d" % count
print "Tuition paid for final recipient: $%.2f" % ftuition
print 'Total number of years fund was operative: %s' % str(year + 1)
my code for number two (this code ends up looping and does not increment the
initial funding, as I had thought it would):
#!/usr/bin/env python
#
#scholarship2.py
#
### initialize values
loop = 1
while loop is 1:
year = 0
count = 0
initmoney = 500000.0 #initial funding
money = initmoney #fund amount
ctuition = 34986.0 #current tuition
rate = 1.041 # 4.1% annual increase on tuition
principle = 1.05 #5% annual interest accrued on fund
### calculations
while money > 0 and money >= ctuition: # while the fund has money and
can cover tuition
if year % 2 == 0: # if this is year 0 or every even year after year
0
money = money - ctuition
ftuition = ctuition
count += 1
print "pass ", count
ctuition = ctuition * rate
money = money * principle
year += 1
if year == 100:
loop = 0
print "The total funding required to last 100 yrs: $%.2f" %
initmoney
print count
print year
else:
print 'restart with new funding'
initmoney += 100.0
year = 0
count = 0
ctuition = 34986.0
This isn't your only problem, but the immediate difficulty you mention,
the incorrect value for initmoney, is caused by initializing said value
inside the while loop. Thus every time you go through the while loop,
it will be set to the same value. Since you want to increment it by
100, you need to move the initialization outside of the loop:
initmoney = 500000.0 #initial funding
loop = 1
while loop == 1:
year = 0
count = 0
money = initmoney #fund amount
...
I think I'd also eliminate the loop variable in favor of a "break" statement.
Make it a while True, and use break when you print out the result.
DaveA
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