Decoding using Frequency Tables

Good afternoon!

Today we will be learning how to use frequency analysis to crack a Caesar Cipher!

Part 1. Collecting data from a small sample.

1. Choose about 100 English letters from a newspaper or other English text. 
2. Work with your group to count the As, Bs, etc., in your sample.
3. Enter your data in this table.

Part 2. Computing relative frequencies.

I have already entered functions to calculate the relative frequencies for each of the letters.  Using the completed data (wait for everyone to finish entering data), answer the following questions with your partner.

1. What percent of the letters in the class sample were the letter T? ____%
2. About how many Ts would you expect in a sample of 100 letters? _____
3. If your sample was about 100 letters, was your answer to 1b close to the number of Ts you found in your sample?
4. What percent of the letters in the class sample were the letter E? ____%
5. About how many Es would you expect in a sample size of 100? _____
6. About how many Es would you expect in a sample of 1000 letters? ____
7. This table shows frequencies of letters in English computed using a sample of about 100,000 letters. How is your class data the same as the data in that table? How is it different? Why might it be different?

Now use our frequency analysis to decode Jenny's message.