In the over-the-counter market, stocks are identified by either a 4-letter or a 5-letter code formed from the 26 letters of the alphabet. What is the maximum number of unique stocks that can be represented with these codes?

Correct answer marked below

2(26)^5

26(26)^4

27(26)^4

Correct

26(26)^5

27(26)^5

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Explanation

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Official Explanation

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In a 4-letter code {XXXX}, each letter can be one of 26 options, leading to a total of

26^4

possible combinations. For a 5-letter code {XXXXX}, each letter also has…

Comments

AnkitaSep 1, 2024

this pattern comes up frequently

PrabhaankAug 26, 2024

Thank you very much!

What this question tests

Whether you can count arrangements and selections correctly — permutations vs. combinations.

Overcounting: treating a selection as ordered when order does not matter, or forgetting to divide by duplicates.