Exploring Probability with Spreadsheets

Birthday Twins

Jay Kesler

You can follow this presentation on your device at
https://slides.com/d/TgYqYF8/live

Open Office365

Open https://sccd-my.sharepoint.com and sign in with your Sierra College account

Create a Spreadsheets Folder

...and open that new folder

Create a New Spreadsheet

Start a "Student" Column

Enter "Student" in cell A1

Enter the number 1 in cell A3

Use a formula for student 2

In cell A4, type     =A3+1

Drag down the magic box

Drag down to row 37 to Give your spreadsheet 35 students

Select cell A4 (the cell with "2" in it)

Color Column A

  • Select Column A
  • Choose the Paint Bucket icon and select a color.

Coloring groups of cells helps you
visually understand what the information is describing

Create a classroom

In cell B1, Type "Classroom"

In cell C1, Type the number "1"

Group these together visually by giving them a color.

Create Random Birthdays

  1. In cell C3 corresponding to student 1 in classroom 1 type
    =RANDBETWEEN(1,365)
  2. Drag the magic box down to give each student a random birthday

Find Birthday Twins

In cell C2, type
=MODE(C3:C37)

to find anybody with the same birthday in this classroom.

Colorize it

In cell B2, type "Birthday Twins" and add some color to cells B2 and B3 by selecting both cells and using the paint bucket.

Create a Second Classroom

  1. Right Click on column C
  2. Choose Copy
  3. Right Click on column D
  4. Choose the Paste icon

Change the Classroom Number

In cell D1, change the value from the number 1
to the formula =C1+1

Make a Bunch of Classrooms

Select cells D1 through D37 (click on D1 and drag down)

Drag the Magic Box to the right many many columns.

Birthday Twins Presentation

By jkesler

Birthday Twins Presentation

Use a spreadsheet to see how likely birthday twins are in a group of 35 people.

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