**Due Date:** Monday, September 24, or Tuesday, September 25,
2007, before the beginning of your lab section.

**Objective:** The main objective of this assignment is to
practice graphical input and output and also input, output with
files.

**Programming assignment:** similar to Programming Assignment
2.

**Reminder:** To protect students against rain, the university
decided to require every student to purchase a special UTEP
umbrella. These umbrellas comes in different size; the cost of an
umbrella is proportional to its area in square inches: 1 square inch
costs 10 cents, i.e., $0.10. Umbrellas are of the shape of a
half-sphere, so the area can be computed as 2 pi times the
umbrella's radius squared. Your program should estimate a cost of an
umbrella for a student and generate a bill. Specifically, your
program should:

- ask the student for his or her name;
- ask the student for the desired umbrella radius (in inches);
- print a bill with the student's name and the cost of the umbrella.

**New features:**

- set up dialog boxes for input and output;
- format the input to 2 digits after the decimal points (as is natural in representing dollars and cents);
- in addition to printing the bill on the screen, store it in a file.

**Homework assignment:** on a separate sheet of paper, solve Ex.
10 and Ex. 12, p. 162.

**Deliverables:** as instructed by your TA.