Answer to Question #300108 in Visual Basic for Sin

Question

Programming Problem 4: Caffeine Absorption

(Note: Programming Problem 4 draws directly on Chapter 6, Programming Project 1, page 285.)

Nutritional Associates of New Jersey stresses to their patients the effects of caffeine on the body. After caffeine is absorbed into the body, 13% is eliminated from the body each hour. Assume a person drinks an 8-ounce cup of brewed coffee containing 130 mg of caffeine, and the caffeine is absorbed immediately into the body. See Figure 6.77 in the Visual Basic text, and write a program to compute the following values: 

1. The number of hours required until 65 mg (one-half the original amount) remain in the body 
2. The amount of caffeine in the body 24 hours after the person drinks the coffee

Suppose the person drinks a cup of coffee at 7:00 a.m. and then drinks a cup of coffee at the end of each hour until 7:00 a.m. the next day. How much caffeine will be in the body at the end of the 24 hours?

Answer 1

<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class Form1
    Inherits System.Windows.Forms.Form

    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        Try
            If disposing AndAlso components IsNot Nothing Then
                components.Dispose()
            End If
        Finally
            MyBase.Dispose(disposing)
        End Try
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.btnCalculate = New System.Windows.Forms.Button()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.txt65mg = New System.Windows.Forms.TextBox()
        Me.Label2 = New System.Windows.Forms.Label()
        Me.txtOneCup = New System.Windows.Forms.TextBox()
        Me.Label3 = New System.Windows.Forms.Label()
        Me.txtHoursCup = New System.Windows.Forms.TextBox()
        Me.SuspendLayout()
        '
        'btnCalculate
        '
        Me.btnCalculate.Font = New System.Drawing.Font("Microsoft Sans Serif", 14.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(204, Byte))
        Me.btnCalculate.Location = New System.Drawing.Point(50, 12)
        Me.btnCalculate.Name = "btnCalculate"
        Me.btnCalculate.Size = New System.Drawing.Size(185, 37)
        Me.btnCalculate.TabIndex = 0
        Me.btnCalculate.Text = "Calculate Values"
        Me.btnCalculate.UseVisualStyleBackColor = True
        '
        'Label1
        '
        Me.Label1.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(204, Byte))
        Me.Label1.Location = New System.Drawing.Point(28, 75)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(118, 42)
        Me.Label1.TabIndex = 1
        Me.Label1.Text = "One cup: When will 65 mg remain?"
        '
        'txt65mg
        '
        Me.txt65mg.Font = New System.Drawing.Font("Microsoft Sans Serif", 12.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(204, Byte))
        Me.txt65mg.Location = New System.Drawing.Point(172, 75)
        Me.txt65mg.Name = "txt65mg"
        Me.txt65mg.ReadOnly = True
        Me.txt65mg.Size = New System.Drawing.Size(100, 26)
        Me.txt65mg.TabIndex = 2
        '
        'Label2
        '
        Me.Label2.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(204, Byte))
        Me.Label2.Location = New System.Drawing.Point(28, 120)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(118, 37)
        Me.Label2.TabIndex = 1
        Me.Label2.Text = "One cup: Quantity after 24 hours:"
        '
        'txtOneCup
        '
        Me.txtOneCup.Font = New System.Drawing.Font("Microsoft Sans Serif", 12.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(204, Byte))
        Me.txtOneCup.Location = New System.Drawing.Point(172, 120)
        Me.txtOneCup.Name = "txtOneCup"
        Me.txtOneCup.ReadOnly = True
        Me.txtOneCup.Size = New System.Drawing.Size(100, 26)
        Me.txtOneCup.TabIndex = 2
        '
        'Label3
        '
        Me.Label3.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(204, Byte))
        Me.Label3.Location = New System.Drawing.Point(28, 171)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(118, 48)
        Me.Label3.TabIndex = 1
        Me.Label3.Text = "Hours cups: Quantity after 24 hours:"
        '
        'txtHoursCup
        '
        Me.txtHoursCup.Font = New System.Drawing.Font("Microsoft Sans Serif", 12.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(204, Byte))
        Me.txtHoursCup.Location = New System.Drawing.Point(172, 171)
        Me.txtHoursCup.Name = "txtHoursCup"
        Me.txtHoursCup.ReadOnly = True
        Me.txtHoursCup.Size = New System.Drawing.Size(100, 26)
        Me.txtHoursCup.TabIndex = 2
        '
        'Form1
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(284, 228)
        Me.Controls.Add(Me.txtHoursCup)
        Me.Controls.Add(Me.Label3)
        Me.Controls.Add(Me.txtOneCup)
        Me.Controls.Add(Me.Label2)
        Me.Controls.Add(Me.txt65mg)
        Me.Controls.Add(Me.Label1)
        Me.Controls.Add(Me.btnCalculate)
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle
        Me.MaximizeBox = False
        Me.MinimizeBox = False
        Me.Name = "Form1"
        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
        Me.Text = "Caffeine Absorption "
        Me.ResumeLayout(False)
        Me.PerformLayout()

    End Sub
    Friend WithEvents btnCalculate As System.Windows.Forms.Button
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents txt65mg As System.Windows.Forms.TextBox
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents txtOneCup As System.Windows.Forms.TextBox
    Friend WithEvents Label3 As System.Windows.Forms.Label
    Friend WithEvents txtHoursCup As System.Windows.Forms.TextBox

End Class

Public Class Form1

    Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
        'calculate The number of hours required until 65 mg (one-half the original amount) remain in the body. 
        Dim numberHours As Integer = 0
        Dim amount As Double = 130
        While amount >= 65
            amount -= amount * 13 / 100
            numberHours += 1
        End While
        txt65mg.Text = numberHours.ToString()

        'The amount of caffeine in the body 24 hours after the person drinks the coffee. 
        amount = 130
        numberHours = 0
        While numberHours < 24
            amount -= amount * 13 / 100
            numberHours += 1
        End While
        txtOneCup.Text = Math.Round(amount, 2).ToString() + " mg"
        'c. Suppose the person drinks a cup of coffee at 7:00 a.m. the next day. How much caffeine will be in the body at the end of the 24 hours? 
        amount = 130
        numberHours = 0
        While numberHours < 24
            amount -= amount * 0.13
            amount += 130
            numberHours += 1
        End While
        txtHoursCup.Text = Math.Round(amount, 2).ToString() + " mg"

    End Sub
End Class