Answer
code
Work Step by Step
# 9.27 (Compare loans with various interest rates) Rewrite Exercise 5.23 to create the
# user interface shown in Figure 9.37. Your program should let the user enter the
# loan amount and loan period in the number of years from a text field, and should
# display the monthly and total payments for each interest rate starting from 5 percent
# to 8 percent, with increments of one-eighth, in a text area.
import math
from tkinter import *
class MainGUI:
def __init__(self):
window = Tk()
frame = Frame(window)
lbl1 = Label(frame, text="Loan amount: ")
lbl2 = Label(frame, text="Number of years: ")
self.lm = StringVar()
self.ny = StringVar()
ent1 = Entry(frame, textvariable=self.lm)
ent2 = Entry(frame, textvariable=self.ny)
lbl1.grid(row=1, column=1)
ent1.grid(row=1, column=2)
lbl2.grid(row=1, column=3)
ent2.grid(row=1, column=4)
Button(frame, text="Calculate", command=self.cal).grid(row=1, column=5)
frame.pack()
self.txt = Text(window)
self.txt.pack()
window.mainloop()
def cal(self):
i = int(self.ny.get())
counter = 1
self.txt.insert(END, "Interest Rate Monthly Payment Total Payment\n")
while counter < 26:
self.txt.insert(END, format(i, "-5.3f"))
self.txt.insert(END, " ")
monthlyInterestRate = i / 1200
monthlyPayment = int(self.lm.get()) * monthlyInterestRate / (
1 - 1 / math.pow(1 + monthlyInterestRate, int(self.ny.get()) * 12))
self.txt.insert(END, format(monthlyPayment, "-5.2f"))
self.txt.insert(END, format((monthlyPayment * 12) * int(self.ny.get()), "-24.2f"))
self.txt.insert(END,"\n")
counter += 1
i += .125
MainGUI()
