# Homework #2

 Due Date: April 14, 2009 Points: 100

## Written Exercises

1. (4 points each) Copy the program avg2.py on page 38 of the text, and do the following:
1. Put a dollar sign “\$” immediately before and after each variable
2. Put a carrot “^” immediately before and after each expression
3. Put a comment at the end of each line indicating the type of statement on that line (output, assignment, input, loop, etc.)
2. (4 points each) Show the output from the following fragments:
1. for i in range(5):
print i * i
2. for d in [3,1,4,1,5]:
print d,
3. for i in range(4):
print "Hello"
4. for i in range(5):
print i, 2**i

## Programming Exercises

Remember to turn in your error logs. For problem 5, you must also turn in the refinement file.

1. (20 points) Modify the convert.py program in Section 2.2 with a loop so that it executes 5 times before quitting (i.e., it converts 5 temperatures in a row). Turn in your program in the file convert2.py.
[text, §2.9, Programming Exercises problem 3]
2. (20 points) As an alternative to APR, the interest accrued on an account is often described in terms of a nominal rate and the number of compounding periods. For example, if the interest rate is 3% and the interest is compounded quarterly, the account actually earns ¾% interest every 3 months.
Modify the futval.py program to use this method of entering the interest rate. The program should prompt the user for the yearly rate (rate) and the number of times that the interest is compounded each year (periods). To compute the value in 10 years, the program will loop 10*periods times and accrue rate/period interest on each iteration.
[text, §2.9, Programming Exercises problem 7]
3. (32 points) Write a program to compute the sum of the first n cubes (that is, each number from 1 to n raised to the third power, and the powers summed). Prompt the user to input n. You may assume that the user will enter a non-negative number. Turn in your program in the file sumcubes.py.

## Extra Credit (Programming)

Remember to turn in your error logs. For problem 6, you must also turn in the refinement file.

1. Do the following:
1. (25 points) Write a program to compute the square of the sum of the first n numbers. Prompt the user to input n. You may assume that the user will enter a non-negative number. Turn in your program in the file sumnsq.py.
2. (3 points) What do you notice about the output from the program sumcubes.py and sumnsq.py when they are given the same n?