Codebusters Test Data-Driven Instruction 4

Question 1

A Codebusters team uses data from previous events to build a letter frequency table. Which statement best describes how to use this table during a timed event?

Accepted Answer

Cross-reference frequency data with word length patterns and common word shapes to narrow substitutions

Answer

Substitute the most frequent ciphertext letter directly for E without checking word patterns

Answer

Ignore frequency data and rely entirely on guessing common words

Answer

Use frequency data only if the cipher has more than 200 characters

Question 2

Tracking student performance, a coach finds errors related to trigraph patterns. What is the most common trigraph (three-letter sequence) in English?

Accepted Answer

THE

Answer

AND

Answer

ING

Answer

ION

Question 3

A student reviews a ciphertext and notes that one symbol appears at both the start and end of many words. What does this structural pattern suggest about the plaintext letter?

Accepted Answer

It is likely a common letter that can begin and end words, such as T, S, D, or N

Answer

It is a rare consonant like Q or Z

Answer

It must be a vowel

Answer

It represents a space or null character

Question 4

After reviewing team data, a coach finds that students rarely consider word-ending patterns. Which letter ending is most common in English words?

Accepted Answer

E

Answer

B

Answer

G

Answer

M

Question 5

A Codebusters team uses data to recognize that doubled letters in ciphertext carry extra information. Which pair of English letters is most commonly doubled?

Accepted Answer

LL

Answer

CC

Answer

BB

Answer

GG

Question 6

Using data from past Codebusters events, an instructor identifies that students struggle with baconian cipher letter groupings. In Baconian cipher, how many bits (A/B symbols) encode each letter?

Accepted Answer

5

Answer

3

Answer

4

Answer

6

Question 7

A data-driven review shows students lose time miscounting groups in a rail fence cipher. If the message 'DATADRIVEN' is encrypted with 2 rails, what is the first step to decrypt it?

Accepted Answer

Split the ciphertext into two equal groups corresponding to the top and bottom rails

Answer

Find the key length using the Kasiski test

Answer

Apply frequency analysis to the ciphertext directly

Answer

Convert each letter to its alphabetical number